


Unscientific Research

by Secretly_a_wuss



Category: Kuroshitsuji | Black Butler
Genre: Anal Sex, Bondage, Bottom Ciel, Bottom Sebastian, Fluff, M/M, Mating Cycles/In Heat, Neko Au, Oral Sex, Romance, Scenting, Slight teratophilia, Smut, Top Ciel, Top Sebastian, glow in the dark dick, neko sex perks, neko!Ciel, scientist!Sebastian, sex in general
Language: English
Status: In-Progress
Published: 2018-06-16
Updated: 2019-05-05
Packaged: 2019-05-24 02:46:13
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 12
Words: 31,094
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14946134
Author URL: https://archiveofourown.org/users/Secretly_a_wuss/pseuds/Secretly_a_wuss
Summary: A team of scientists arrive at the newly discovered Toboso island. Sebastian a young and plucky zoologist, on one of his expeditions alone on the mysterious island, encounters a never before seen creature. It appears to be some mix of man and cat, the creature has a relatively human body aside from its cat ears and twin tails. Despite his role as an animal researcher Sebastian accidentally falls in love with the strange humanoid cat creature and names it Ciel, the creature seems to be equally enamoured and makes his interestwellknown.





	1. First Encounter

**Author's Note:**

> This little story will be the first proper smut I've written. It isn't going to have a serious complicated plot and is just a bit of fun

At 4:00 pm a specialised team of expert scientists, mainly consisting of zoologists landed on the never before explored Toboso island. The island was situated in the middle of the Pacific Ocean between Australia and South America, and took 2 weeks to get to by boat from Port Jackson in Sydney. They brought with them enough equipment and supplies to survive for around 3 months, however, their expedition was only scheduled to last for a single month, should something go wrong they would not starve. Within their handpicked team they had mostly zoologist researchers, a chef, a few assistants to help set up camp and aid in research, and a medical doctor who specialised in toxicology. Islands were generally fairly devoid of dangerous predators, as the small environment meant less diversity in species and therefore, less competition. However, the reported dense rainforest that covered half of the island worried the head of the research department, and so a well trained doctor had been added to the team just in case anyone was bitten by something venomous, it increased their odds of being able to treat an injury successfully. 

Sebastian wasn’t worried about the unknown though. The plucky young zoologist was eager to start doing real research in the field. Toboso island had never been seen with the eyes of men (as far as they knew) and so the work he would be doing here was breaking new ground and would show the world sights previously unseen. He was excited as he quickly carried a box full of packets of dehydrated food to the largest tent that would soon become the cafeteria and mess hall. He ducked inside the tent flap, strolling past iron polls that held up the huge tent to dump the box with the rest of the kitchen supplies. He adjusted his glasses that framed his unusual crimson eyes, when this was finished he would be able to start exploring. Although he wasn’t looking forward to working with the other scientists, he preferred the peace and quiet of studying nature alone. Sebastian didn’t mind doing the paperwork side of research with other people, but when he was cataloguing new species and photographing the animals he found, he preferred to be by himself without any distractions.

\--

Sebastian was the most distracted he had ever been in his life. 

He had stopped for a lunch break by himself. Sebastian had succeeded in convincing the manager and head scientist of the expedition to let him study and explore the island on his own, as long as he was careful and carried a radio with him at all times, checking in every 2 to 3 hours to make sure he hadn’t died or injured himself, he was allowed to explore by himself. And while there were currently no other humans about his lunch had gone missing. He had only turned away for a moment to look at and photograph a large beetle that had a bright yellow and blue shell, but when he turned back to his packed chicken sandwich that had sat on top of his bag, it had disappeared. 

He didn’t understand where it could have gone, he was alone out here and the largest thing he had seen was a seabird on the shoreline earlier. But he was currently about 3 hours of hiking into the rainforest and had not seen any animal bigger than his palm since. He checked behind his bag, lifted it from the ground, looked inside it in case he had actually never taken it out in the first place, and even emptied and repacked the entire contents of his bag.

His carefully crafted chicken sandwich was gone. Stolen from him by the universe… or by whatever had left behind the two slices of bread and portion of lettuce. He kicked the ruined bread with his foot, it had a bite taken out of it but was otherwise untouched. He had really been looking forward to that, but the mystery of it made him more curious than mad.

Then he saw it. The most stunning creature he had ever laid eyes on. At first it appeared to be a man but two cat like blueish tails flicked beside him, he was delicate looking, flat chested and with matching cat ears on top of his head, nestled within soft blue hair. He had one electric blue eye, the other one a vibrant violet. The man was naked, skin pale and soft in the low light of the dense forest, but the scientist couldn't see a penis, instead the creature appeared to have some kind of vertical slit on his hairless neither regions. Sebastian's zoologist training makes him think that it may be female before he notices the small pair of balls nestled between the creature’s legs. _Perhaps the sexual organs are internal? _He doesn’t know enough to be certain, it’s all simply a hypothesis at the moment, and he can’t decide its sex, male or female?__

__The creature comes hesitantly closer and crouches to pull and prod at his backpack with a dainty looking hand, the being tilts its head expectantly, perhaps asking for more chicken from his sandwich. This creature is otherworldly, it’s only a few inches shorter than him and it has a lean but muscular build, there’s something about the creature that takes his breath away. Sebastian had always loved cats, it was why he became a zoologist, but he could have never predicted finding something like this._ _

__“I don’t have any more food” he says quietly when the creature meows at him, like a kitten asking for seconds. But he wants to give this beauty all the chicken in the world, he’s so stunning and majestic, he’d do whatever it wanted. Sebastian finds that he can’t move as the creature stands back up and stalks towards him, it lays its hands on his chest and the atmosphere is so hot, he thinks he might faint. He achingly slowly raises a hand to stroke the cat human hybrid, his black painted nails run through the feather soft locks of sea blue and he even risks rubbing the soft furred skin of the one of the cat ears between two fingers._ _

__The creature leans into him and Sebastian can hear a rumbling purr vibrate through its chest. He massages the base of the ear, raising a second hand to better stroke the mix of man and cat. The cat man kneads his chest with his hands, claws extend and retract from the tips of his deceivingly gentle fingers, but they don’t really hurt so the scientist doesn’t mind. It's actually very cute. The creature rests its head on his shoulder, body pressed close and eyes closed as it enjoys the sensation of Sebastian’s hands running through its hair._ _

__Sebastian may have just messed up. Because he’s a professional zoologist and wildlife researcher, and he might have just accidentally fallen in love with a strange humanoid cat creature. Neko, that’s what this never before seen species would be called. Of course, they would need to be classified and given a proper scientific name, but for now he would name this one Ciel._ _

__The neko moved its hands to his face and held him still as it crushed its soft pink lips to his own, he was so startled he froze and the creature pushed its tongue passed his own lips and inside his mouth. Rough and cat like it, with little tiny bristles on it, the appendage tasted him, running along his teeth and swiping across his unresponsive tongue. He didn’t know what to do and by the time he had rebooted and was thinking logically again, the creature had already pulled away with a cheeky fanged grin._ _


	2. Observation

**Summary for the Chapter:**

> Ciel was like something out of a dream, and Sebastian couldn't believe just how quickly he had fallen head over heels for the neko...

**Notes for the Chapter:**

> The support on this fic has been beyond amazing, thank you all so much!  
> Also there will be some spicy chapters coming up soon, and I have some art planned for this fic as well. I have a tumblr blog dedicated to  
> Black Butler fanart for anyone whose interested, I'll be posting chapter updates there as well as art for this fic. https://www.tumblr.com/blog/secretly-a-wuss I have the same username there @secretly-a-wuss

“We can learn languages by kissing” the creature told him. Its voice was light but masculine, lending more evidence to the hypothesis of it being male with internal sex organs rather than female. The fact that it was able to speak perfect English just by kissing him was astounding, it could have been something out of a science fiction novel. The scientist shouldn’t be thinking about how smooth and soft that voice was, how he’d love to hear the neko whisper his name longingly. But Sebastian’s mouth still tingled with an odd heat from their kiss and his cheeks burned hotly at the memory of it, he couldn’t help it, the creature _was _completely naked after all.__

___“What are you?” Sebastian asked in disbelief._  
The neko frowned “I’m me” although Ciel had managed to learn human language almost instantly, there appeared to still be boundaries to his understanding.  
“I’m human and my name is Sebastian, if your species doesn’t already have a name can I call them nekos?” the scientist asked. He could have never predicted that the neko would be capable of speech, it was a revolutionary scientific breakthrough to be able to properly communicate with another species. There had never been an animal that could actually speak and understand human language before, there were apes that had learnt sign language and birds that could mimic words, but this otherworldly creature before him was on an entirely different level. 

___“I think I understand…” the cat man tilted his head, “we don’t name things like that, there is only us and prey that either walk, swim or fly”_  
“What about plants or rocks?” Sebastian asked, he was learning so much already.  
The neko shook his head as though the man was asking to many unnecessary questions, “small green” he pointed to some low lying bushes, “up high” he pointed up to the nearest tree, “soft ground” he finished by pointing down to the forest covered in leaf litter, roots and damp dirt. Sebastian didn’t really understand that last one, how could dirt be soft? 

___“Do you have a name, are there any others of your kind about?”_  
“No I am me, and I am the last. The rest made themselves small so they would not starve, and became the prey that I will not eat”  
“Can I call you Ciel then? Also, what do you mean by made themselves small, did they die or something”  
“I will accept that name, and we can choose to give up this form, to become small and covered in fur, but once one of us changes they cannot change back” sorrow crossed the neko’s face and Sebastian’s heart tightened as he realised that he was looking at the last of a species. Ciel wasn’t just critically endangered, he was a dying race, possibly the last of a whole intelligent civilisation that hadn’t been able to sustain itself on this island. The others must have turned into the jungle cats some of his team had reported finding, although he hadn’t actually seen any of the cats himself he had seen photos from his fellow researchers. From memory the jungle cats also had two tails, although a plausible theory had yet to be made as to why they had this adaptation, it must have been a leftover trait from when they were nekos. 

___This magical creature with two tails and duel coloured eyes was incredible, but Ciel must have been so lonely on this island all by himself._  
“You’re incredible” the scientist stepped closer hands raised, he wanted to pat Ciel again but he wasn’t sure if the neko would be okay with it “I’ve never met anything like you before” Ciel blushed at his words, head tilted down to hide his eyes behind his bangs.  
“Wait, you stole my sandwich!” the scientist frowned, his stomach reminded him by grumbling in annoyance. Ciel hissed, his tails puffed up and he revealed sharp cat like fangs and incisors as he snarled, the neko bolted into the undergrowth, twin tails disappearing with him into the bushes. 

__Sebastian picked up his bag, defeated, the neko was far too quick to follow and what would he even do anyway if he caught up to him.  
“I guess he was hungry… I hoped Ciel enjoyed it at least” he sighed and began his long trek back to camp. Meeting Ciel had felt surreal and he was half convinced that it was all a dream and had actually never even happened, but his lunch was missing and his lips and the inside of his mouth still tingled, so it had to have been real._ _

__When the scientist could see the shoreline and the silhouettes of his camp, he felt relived and excited for food, finally he’d be able to dump this heavy backpack and relax. The entire walk back all he had been able to think of was the neko’s soft ears and hot tongue, he could have never predicted that he’d be smooched on this expedition by a cat creature and still couldn’t decide how he felt about it._ _

__But before he was able to leave the forest and return to civilisation, he was yanked backwards and spun around. It was Ciel! The strange creature held a medium sized silver fish in his mouth and was looking at him with intense purple and blue eyes. The pupils shrunk in the higher light levels that reflected off the sand and formed distinctly catlike slits, how much biology did nekos and cats share?  
“Ciel?” the neko took the fish from his mouth and pushed it to Sebastian’s chest, he automatically grabbed it and almost shuddered at the feeling of the cold wet and scaly flesh of the dead fish. _ _

___“Eat it” the neko demanded._  
“Uhhh” Sebastian hesitated, he glanced down at the fish with a neat row of teeth marks in it. The expedition wasn’t allowed to hunt on the island, it was part of the reason they had brought so many supplies. But at his delay Ciel frowned, nose scrunching up as his eyes watered.  
“I caught it for you, is it not good enough?” the neko sobbed a little, ears flat on his head.  
Sebastian panicked “it’s great! I love it!” he assured the neko and grabbed one of Ciel’s hands to hold in his free one, the other occupied awkwardly with the fish. Ciel’s hand had soft long fingers and fit perfectly in his own, the neko brightened a little and he never wanted to let go. 

__“Aren’t you going to try it?” the neko asked, his tears temporarily halted.  
“Uhhh” Sebastian hesitated again. He looked at the limp and very dead fish in his hand, he was a respected zoologist and animal researcher and he was apparently going to take a bite out of this raw fish to please a strange new lifeform. One that was looking at him expectantly with literal kitten eyes. How could he possibly say no._ _

___He raised the fish to his mouth, closed his eyes and took a bite. It was disgusting, mildly salty, uncooked and scaly._  
He chewed and nodded his head “it’s good, but I’m actually not that hungry… you should take the rest” he handed the fish back and luckily Ciel accepted it.  
“Okay… but you liked it, right?” the neko’s ears rose expectantly, his tails swished softly back and forth in excitement.  
“Yes I did, thank you”  
“Now we’re even, I’m sorry for taking your food, even if half of it was gross and not meat. I was just curious”  
“It’s fine” he brushed it off. If losing a sandwich meant he got the chance to meet Ciel, then he’d always chose losing the sandwich. 

__The neko quickly captured his mouth in another kiss, this one gentle and sweet, and nowhere near as long or thorough as the first one. Ciel brushed his strange bristly tongue over Sebastian’s lips once and pulled away before the scientist could kiss him back.  
“See you around… _Sebastian _” the neko winked and blushed furiously. With a smile equally as cheeky as the last time they kissed, he sprinted off into the forest with his half eaten fish. The zoologist touched his warm lips with the tips of his fingers, surprised to find them tingling again, his heart was beating furiously and he was sure he was blushing again. That seemed to be all he did around Ciel.___ _

____Sebastian went back to his camp and Ciel to wherever Ciel lives. He didn’t end up telling his colleagues about the new species, not yet anyway, besides, he never got a photo so he didn't have any proof to show them of the neko anyway. As he laid in his sleeping bag, wide awake and staring at the dark roof of the large tent, he couldn’t stop his very unscientific thoughts about the adorable creature and the unexpected kisses they had shared that day. Strangely enough, he found that he wanted another, in fact, he wanted lots of them, he’s fallen head over heels for that cheeky cat and doesn’t know how he can possibly survive a month on this island if the neko keeps kissing him._ _ _ _

____\--_ _ _ _

____The neko first saw the beautiful man wandering by himself around the rocky shores of the north side of the island. At first, he wasn’t quite sure of its gender. The pelt it sported covered it from head to toe, with only its face and arms hairless, but when the wind blew its scent over to where the neko was hiding in the bushes and the creature had smelt like a male. He knew that the new creature had silky black hair on the top of its head and looked like him (lacking only his large ears and two tails), but he never got near enough to determine if those crimson eyes were as stunningly red up close as they were from a distance._ _ _ _

____A large group of the creatures had arrived in a strange contraption from the sea only a few sunsets ago, but the red eyed one was different. He was not as noisy as the others, he didn’t yell or crash through the forest, all he did was quietly look at and record the prey and green of the island, occasionally drawing quick pictures on a white rectangle, but mostly he used the odd hand held device to look at the prey. The neko didn't think that these creatures were prey, it would be very difficult eat a whole one by himself and he was not one to go to all the effort of catching something only to let it go to waste. He'd much rather sleep of a warm rock and wait for something smaller to come along. Oddly enough he found that he _was _hungry for the red eyed creature..._ _ _ _ __

____For too long the neko simply watched him from afar. He touched himself to the thought of the new creature, the pretty one, not the other ugly ones that were wrinkled with age or oddly proportioned. He knew that he shouldn’t, but he couldn’t help himself. The neko noticed that the creatures could take off their pelts and added that to his fantasies too, given the chance he would take his creature (the cute one) to his den, remove all of those pesky pelts and claim his smooth creamy skin with everything he had. He wondered what the male would taste like, wondered how similar their bodies were, and how much of the new creatures' pelts were actually permanently stuck to them. What sights were hidden from his eyes?_ _ _ _

____He felt slightly pathetic, getting off on some stranger that was not even a member of his own kind, but he was so lonely, there weren’t any more of his kind left, they all gave up. His pretty creature was always by himself when he wasn’t in one of the square dens, so perhaps he was lonely as well. It was with that thought that he saw the odd flat square smelling of cooked meat out in the open, the cutie’s back was turned and so he snatched and ate it on impulse. The meat was good, but his creature had added odd green stuff, and something cream coloured and soft which tasted like nothing, so he only ate the meat and left the rest._ _ _ _

____The neko kissed the creature, he tasted a little funny but it wasn’t bad in the least, it was actually quite good. With this new tongue he could talk to the man named Sebastian. He was a human, and thought he was incredible, and named him Ciel, and made him blush. But the man was irritated that he stole his human food, and so the overwhelmed neko had ended up running away, and it was then that he knew he'd just fucked up any chance of ever being with the gorgeous red eyed creature. Ciel just wanted to hide for the rest of the day and forget all about the stupid human, but he ended up feeling bad about how they parted. Ciel _did _steal Sebastian’s food, so he decided to make it up to the human and caught him a nice looking fish. At first his human didn’t seem to like the fish, but Sebastian took a bite out of it and said that it was good so Ciel had to believe him. The neko couldn’t stop himself from kissing him again before they parted, the man tasted too good, and he was already addicted to that taste.___ _ _ _

______Ciel decided to court the human, his pretty and adorable Sebastian with the gorgeous scarlet eyes that _are even more _stunning up close then they are from a distance. He realises that he hasn’t been this happy in years and he can’t wait to see the man again.___ _ _ _ _ _

________Ciel loves this odd creature and is determined to show his adoration to his beloved. And when he sees Sebastian the next day lying on his stomach and staring at a small lizard with that same strange machine he carries, he knows that he has to step up his courting efforts. The neko spent all day collecting these, so he hopes that his human will like them..._ _ _ _ _ _ _ _


	3. Experimentation

**Summary for the Chapter:**

> His human was terribly obtuse, Ciel would have to pull out all the stops to make the scientist realise his _intent _...__

**Notes for the Chapter:**

> Sorry for the delay, shit happened, but enjoy this brand new fresh out the oven chapter, full of steamy goodness and more blushing. Also my friend Demonofphantomhive made some amazing art for this https://secretly-a-wuss.tumblr.com/post/175057094033/demonofphantomhive-ciel-decided-to-court-the IT'S SO GOOD

The Lizard he was trying to get into focus with his camera shot off across the rocks, it scuttled between the cracks of the stone face of the island and disappeared from sight. He frowned before noticing a cat eared shadow on his left. The scientist looked behind him “Ciel?” he started to push himself up off the ground he had been lying on, but a large weight plopped itself down on his back and pinned him. Ciel pushed his face into the stone beneath him with one clawed hand and took a large sniff of his exposed neck, the neko’s hot breath made him shudder.

“Uhhh, hello to you too?” Sebastian awkwardly mumbled. The neko licked him with his strange bristly tongue and Sebastian shivered at the tingling heat that ran through him. The cat creature remained stubbornly seated, but pulled away from the scientist's neck and sat upright. Sebastian couldn’t think about Ciel’s soft thighs were straddling him, or the fact that the neko’s bare ass was seated firmly on his lower back, he couldn’t think about how this situation would be so much better if he were only facing the other way. He’d had enough of those unprofessional thoughts last night…

“I have a present for you” the neko announced. But only after he had stretched languidly, claws pricking Sebastian’s shoulder blades, did he climb off the human.  
“What is it?” the zoologist asked. He was blushing furiously, but still managed to stand up and check the recent pictures he took with his camera. Ciel shoved a bundle of exotic blue flowers into his arms, the neko’s cheeks were heated as well and he averted his gaze, refusing to make eye contact with Sebastian.

Each individual flower was about half the size of his palm, but together they formed a sizeable bouquet. He had never seen this species of flora before on the island, he was sure that he would have remembered their stunning bright colour because they matched Ciel’s electric blue eye so perfectly. Little petals spread apart at the base, similar in shape to a lily, but the centre of the flower held an intricate clutch of petals that curled together and formed a tube like shape. The scientist had never seen such a strange flower before, it looked like something a hummingbird would drink out of. He didn’t know what to do with them, but found his heart pounding anyway at the small gesture, Sebastian couldn’t keep the smitten smile off his face.

“For me?” He asked stupidly and Ciel furiously nodded in reply, his cheeks an adorable shade of red.  
“Who else would I give them to, the other humans are ugly”  
“Oh” the scientist said dumbly, _did that mean Ciel thought he was pretty? ___  
“What were you doing?” the neko asked to fill the awkward silence.  
“I was just taking a few photos of that lizard. Our team has been sent here to collect as much information as possible on the island and its native fauna and flora. Here, look” Sebastian flicked through his camera roll to find the pictures he had taken of the lizard before Ciel had accidentally chased it off.  
“Wow! How did you capture the prey and make it so small?” the neko peered intensely at the screen, ears swivelled forward in interest.  
“It’s only a flat copy of it, like a drawing. Did your species have any art or stuff like that”

__The neko tilted his head “there are old drawings in the caves, but the prey on those walls are nothing like your… photograph” he tried out the foreign concept, and while he understood the language, there was nothing really like it on the island to compare.  
“Smile!” Sebastian raised the camera. Ciel frowned and pouted, but the scientist still took a photo._ _

“You look great” he showed the neko the image and Ciel was amazed to see his own face on the little screen.  
“It’s like a mirror!” he exclaimed and Sebastian heart was warmed by the wonder on Ciel’s face.  
“I actually have a lot of work to do today, I need to get as many pictures as I can for the next batch of reports. The manager wants them in by Friday and it’s already Tuesday” Ciel merely blinked at him, the scientist having forgotten that the cat probably didn’t know what half the words in his sentence even meant. Sure, Ciel had learnt his language, but he still had only ever lived on Toboso island isolated from human society.  
“I’m busy” Sebastian summarised and the neko’s face fell. 

“But what about me!” Ciel whined. He pulled on Sebastian’s shirt sleeve and made his pupils expand, although the light hurt his eyes a bit, it had the desired effect of making him look utterly adorable.  
“You can hang around, but I need to take pictures of the wildlife here” the scientist stroked his blue hair and rubbed his ears in an attempt to please him.  
“Fine” the neko begrudgingly conceded. 

__However, as the day progressed, Ciel grew more and more distracting. He lounged on rocks, twisting and rearranging himself every few minutes, and generally lazed about seductively. Eventually the neko grew bored and started trying to lie on the scientist whenever he sat down to take a photo. It was so immensely difficult to ignore the neko’s smooth hairless skin and lean but graceful limbs, especially when he seemed to be purposefully posing as inappropriately as possible before him. At one point Ciel rested on his front with his rump in the air, tails swaying as he relaxed in the sun, it would have been fine if Ciel's rear hadn't been facing him, the scientist almost had the feeling that he was doing it on purpose, before dismissing the idea. Sebastian had to assume that Ciel didn’t know how suggestive he was being. It wasn’t like Ciel had access to clothes, he just had to look away, lest Ciel’s perfect ass prove too distracting..._ _

__But during Ciel’s ‘stretching’ Sebastian caught sight of his little light blue toe pads, they were adorable and the scientist couldn’t help running his fingers over them. The act made Ciel giggle, the light brushes on the soles of feet ticklish.  
“You have toe beans! So cute” the scientist’s work ethic was quickly overridden by his love of cats. He decided to ‘have a break’ and grabbed Ciel’s hands to inspect. Sadly, they didn’t have the same blue coloured pads as his feet, but Ciel did let him play with his nails. Sebastian pushed down lightly and watched the claws extend and retract, fascinated by the exquisite design._ _

__“You’re so pretty Ciel” the scientist mumbled as he stroked the fur on Ciel’s two soft tails. The neko couldn’t respond, he had been trying to get the pretty human to notice him all day, but now that he had it, he couldn’t build up the courage to put Sebastian’s inquisitive hands where he wanted them.  
“Oh, that reminds me” the scientist dug through his backpack, “I brought you some more chicken since you seemed to like it last time” _ _

__The neko didn’t know what to say, he was touched that the human had thought about him. Giving gifts was a common courting practice and providing food showed that the gift giver was skilled enough at hunting to take care of a mate. Perhaps, his efforts were finally being understood, the scientist wanted to take care of him!  
“Thank you, Sebastian” Ciel blushed and hugged his human, before eating the food happily._ _

__The attention didn’t last however, as the man all to soon remembered that he had a job to do and went back to ignoring Ciel.  
“I’ve just got to take a few more photos of this bug” he explained. All Ciel could do was pout and curse quietly, he had lost his only chance to do something more intimate, the scientist now pouring all of his attention back into his work. If only he hadn’t been distracted by food._ _

__Throughout the day Ciel stretched and purred and rubbed his chin against Sebastian’s shoulders when he wanted pats (which was often). Like a cat desiring to be fussed over when one was trying to work at a computer, he couldn’t escape Ciel’s constant silent begging, and the worst part was that Sebastian didn’t want to ignore Ciel. He wanted to pull the neko into his lap and spend the rest of the day kissing him, but if he didn’t get these photos done then he’d fall behind on his research, which was the whole reason he was even on this island._ _

__\--_ _

__The neko was frustrated, his human didn’t seem to understand the gift at all. He tried to make his point in other ways, and spent all day posing for and scenting his human, but that didn’t seem to get through to him either. These were his best courting moves and he was being completely ignored! He thought he might have finally gotten through to his human when he started playing with his claws and petting his tails, but it was no use, after he had given Ciel the chicken he soon went back to doing his ‘work’ which the neko was quickly growing to dislike. Finally, Ciel decided that it was time to use his trump card, with this he was sure to get the attention of his human and hopefully would have Sebastian in his nest and begging for him by the end of the day._ _

__Ciel’s hand crept southwards, lingering playfully around his stomach before it ran over his slit. He would show his human _all _that he had to offer, the neko smirked, sure that his mating display would finally sway Sebastian, he would just have to show the man something he couldn’t ignore. But then he heard the crunch of heavy footsteps on leaves and voices talking loudly. _Ugly humans! They ruin everything… _______

______Ciel hissed and slinked away into the trees nearby to escape through a small tunnel that lead to his complex of caves. He left behind a confused scientist and his gift of vibrant blue flowers, his efforts spent trying to win Sebastian’s heart, wasted…_ _ _ _ _ _

______\--_ _ _ _ _ _

______“Ciel?” Sebastian called out. The neko had hissed and disappeared, but left without explaining anything and by the time he had put his camera down and turned around Ciel was long gone._ _ _ _ _ _

______“There you are Michaelis, we’re having a staff meeting at 4 and thought we’d pick you up as we headed back” a couple of his colleagues appeared and he understood then why the cat had fled.  
“Oh, thanks, I forgot about that” the scientist packed away his camera. He couldn’t help feeling a little disheartened that Ciel had left without even saying anything, they hadn’t even been able to share another kiss goodbye. _ _ _ _ _ _

______“Hey, you’re not supposed to pick flowers and mess with the ecosystem” one of the scientists frowned, he was a pudgy man with balding hair.  
“They’re just flowers, relax” Sebastian shrugged his colleague off, he couldn’t go and explain that a humanoid cat creature had given them to him. One that learnt languages by French kissing, wore no clothes, and was drop dead gorgeous. He hoped that no one else would question him about it, because he really wanted to keep the special gifts, it would be heart breaking to leave them behind, or worse, throw them away._ _ _ _ _ _

______“I’m sure your lady friend will love them, now come on, let’s go before the manager complains about us being late” another scientist added and Sebastian let the man assume whatever he liked._ _ _ _ _ _

______\--_ _ _ _ _ _

______Sebastian wrapped a towel around his waist, the tropical climate warmed the campsite, so he wasn’t cold in the ‘shower tent’. There was no plumbing on the island, all they had was a basin of hot water from the filter machine and a waterproof tent for privacy. He missed running water, but a sponge bath was better than nothing._ _ _ _ _ _

______He heard the tent door be unzipped “hey! A little privacy” the scientist frowned, glad that he had put a towel on before the unwelcome interruption. He turned around to ask why they couldn’t simply wait their turn, but was stunned to instead see Ciel once more standing before him. It reminded him of when they had first met, except this time they were both naked, a small towel the only thing hiding Sebastian’s private parts._ _ _ _ _ _

__________The neko approached him slowly, duel coloured eyes practically glowing in the dimly lit tent, and as Ciel moved the light reflected off his eyes like mirrors.  
“So, this is what you look like, under all your pelts…” the neko lightly traced his soft fingers over Sebastian’s chest. When had he gotten so close?  
“Ciel, what are you doing here”  
“I don’t want the other humans to know about me, have you told them?”  
“No-”  
“Good, but you’ll have to be quiet then” Ciel wound his arms around the scientist and pulled him closer, capturing his mouth in another heated kiss. 

__________Sebastian couldn’t stop himself from melting into it, he grabbed the neko’s hair in one hand, the other drifting down to hold onto Ciel’s hip. Claws pricked his back and the neko’s textured tongue forced its way inside his mouth, lighting him on fire.  
“Ciel” the scientist breathed out when they parted.  
“You ignored me all day…” the neko whined and started kissing and licking his neck, each stroke burned his skin, he felt his knees already grow weak.  
“I’m sorry” he’d been blind to the neko’s intent, had assumed that Ciel didn’t know how appealing he had looked spread before him, had foolishly believed that their previous kisses meant nothing.  
“It’s fine” Ciel suddenly bit down on his shoulder and Sebastian got the feeling that it wasn’t fine at all. Although it didn’t break the skin, the nip still left a red mark.  
“You had to do your stupid work, but now I’m going to _make you _pay attention to me” the neko pulled at the white towel and it fell away, revealing Sebastian’s excited member.__

________The neko quickly fell to his knees, he’d never seen a human up close like this before, and he didn’t really know what he was doing, but he was knowledgeable enough to be confident that he could make Sebastian feel good. He reached out and grabbed a hold of the sizeable length before Sebastian could protest, finding that he needed two hands to cover it completely. The skin was soft and flushed red, the length overall stiff but dry. He palmed it a few times, massaging the hot flesh before he removed a hand to anchor himself by holding onto Sebastian’s hip. As he lapped at and wetted the cock with kittenish sucks, licks and kisses he explored his new toy, tasting the salty sweet beads that came from the tip and kneading the rest of the length with firm but gentle fingers. Ciel’s tongue lit a divine fire across his skin, Sebastian had never been this sensitive in his life and Ciel had barely even started. The neko revelled in the moans Sebastian couldn’t contain and felt himself slowly becoming excited._ _ _ _ _ _ _ _

________“Be quiet human or your friends will start to wonder what all the noise is about, you wouldn’t want them to find you getting your cock sucked would you?” he teased and took the head into his mouth. He dug his tongue in the slit, wanting more of the new taste, before sliding his slim tongue over the head.  
“Ah!” Sebastian cried out. He gripped the neko’s blueish hair and barely resisted bucking into his hot mouth, it probably wasn’t a good idea considering Ciel’s sharp teeth. The odd texture of the neko’s bristled tongue should have been uncomfortable, but it merely made him want more. It wasn’t anywhere near as rough as a domestic housecat’s, but didn’t have the same softness of a human tongue. And as it rolled over the glans, pulling at the skin there, the saliva on his cock burned and tingled pleasantly. The scientist finally realised that he wasn’t just aroused, but that Ciel’s spit was actually doing something to him. Now that he thought about it, every time Ciel’s spit had touched him, he had felt tingly._ _ _ _ _ _ _ _

______________“Ciel, what’s- ah!” the neko took him a little deeper and his tip rolled deliciously against the ridges on the roof of his mouth. Fuck, Ciel’s mouth was definitely not human, the odd long and thin tongue wrapped around and squeezing his cock only further proving it. Ciel turned Sebastian’s legs to jelly as his hand still pumped what didn’t fit inside.  
“Your spit…” he panted as pleasure rolled through him.  
“It feels funny” was the best explanation to he could manage, Ciel pulled off with a pop to look up at him, eyes glowing.  
“neko spit…” he around licked his mouth, savouring the taste “it makes things feel good” he reached between his legs and swiped at his dripping slit collecting the dampness there “but this feels better” 

________Ceil ran his wet fingers across Sebastian’s length and he had to bite down on his lip to stop himself from yelling out loud at the sheer pleasure that exploded across his skin, his impossibly hard cock throbbed and he knew that he was close. The neko closed his mouth around the member and took it in as far as his small mouth would allow, being mindful of his sharp fangs and front incisors, he didn’t want to hurt his partner. The teeth at the back of his mouth were far closer to regular human molars, the front set all designed for consuming meat, but he was determined to devour this new kind of meat..._ _ _ _ _ _ _ _

________The tip brushed the back of his mouth and Ciel fought his gag reflex to focus on sucking and licking the length. Ciel loved the hot flesh in his mouth, the weight of it on his tongue and the taste of it as pre-cum leaked from the tip. He moaned, the vibrations further stimulating Sebastian.  
“Fuck, Ciel I’m gonna-” he tried to warn the neko, but Ciel merely doubled his efforts, claws dinging into and scratching the scientist’s hips, he moved his head back and forth, bathing Sebastian in sensation and heat._ _ _ _ _ _ _ _

______________Cum flooded the neko’s mouth as Sebastian moaned, eyes squeezed shut as he struggled to stay upright.  
“Mr Michaelis?” a voice asked from outside the tent and the scientist froze, dread clashing with the high from his orgasm.  
“Are you still using the ‘shower’, I just wanted to pop in before it got too late” another scientist asked from outside. It sounded like a woman, but he didn’t know who from the voice alone.  
“Uhhh” his brain was dead and Ciel merely looked him with another mischievous smile licking cum off his lips, his tails swaying with his own excitement.  
“I actually forgot a towel, do you think you could grab one from my tent, I’m number 27” he quickly bullshitted.  
“Oh, um sure, everyone forgets every now and then” the woman left and Sebastian quickly shoved his towel into Ciel’s arms. 

________“Go, get out of here!” he told the grinning neko, Ciel unzipped the tent and disappeared into the night.  
“I found a spare towel” the woman told him from outside and Sebastian reached a hand out to retrieve it, he wrapped it around himself and left the shower tent with a flush on his cheeks at the memory of what Ciel had just done._ _ _ _ _ _ _ _

________\--_ _ _ _ _ _ _ _

________Ciel could hear the other human approaching the oddly shaped structure, but he also knew that Sebastian was close from the way he moaned so loudly and wantonly, so he persisted. The neko could feel his slit opening, revealing blue skin inside and causing more slick to run down his thighs. Sebastian didn’t notice, too lost in his pleasure and perhaps that was for the best, now that he had seen just how different they were down there, he was suddenly frightened of scaring off the scientist. His human came, pouring salty seed over his tongue which he eagerly swallowed, but their unwelcome visitor had also arrived outside the tent and now Ciel needed to disappear or risk being discovered. Sebastian somehow managed to make an excuse and he was given a window of opportunity to escape, towel in hand he left his love behind._ _ _ _ _ _ _ _

________It was difficult to run with the stiffness between his legs though, his erection had made itself well known and by the time he reached the safety of the trees he fell to the ground, hands desperately stroking himself. He rocked into his palms, knees still sore from kneeling on the strange smooth floor of Sebastian’s bathing den. Ciel held tightly onto the towel, it smelt like his human so he buried his nose into the scent and rutted against it. The cotton was harsh against the sensitive velvety skin of his cock, but the scent of Sebastian drove him to completion, he could almost pretend he was burying himself in his love if he just focused on the smell._ _ _ _ _ _ _ _

________How embarrassing, he hadn’t even been able to make it to his cave, and now he had completely ruined Sebastian’s towel, it was covered in slick and cum, losing much of the scientist’s scent. He was satisfied that he had at least made his feelings well known, the human couldn’t possibly ignore him now. But he also had a new fear, they were not as similar as Ciel had imagined they would be, what if Sebastian saw what was between his legs and decided that he didn’t like it…_ _ _ _ _ _ _ _

**Notes for the Chapter:**

> This is the first proper smut I've ever posted, I hope it was alright, constructive feedback would be much appreciated


	4. Discovery

**Summary for the Chapter:**

> Ciel returns the next night and our duo compare biology...

**Notes for the Chapter:**

> Some italics were messed up in the last chapter, I posted it late at night and probably didn’t preview it before posting, sorry if it looked a little weird, I’ve fixed it all now. Enjoy the new chapter!

The zoologist had been busy writing up reports, he hadn’t been able to step foot out of his tent all day, and as the sun set the only thing he could be grateful for was the cool change that was sure to come with nightfall. It might make the heavy and hot air a bit more bearable as even in his lightest short sleeved shirt he still felt sweaty and overheated. The worst part was that due to all the paperwork he needed to do, he couldn’t find any time to explore the island and therefore, had not seen his beloved neko. He missed Ciel, missed his duel coloured eyes and his soft navy hair. Sebastian was astounded that the neko had feelings for him, and still couldn’t look at the shower tent the same way. He hoped no one had heard them, or unflattering rumours might spread.

The scientist closed his laptop and removed his glasses, deciding that it was far too late to bother with anymore work, perhaps he’d be able to see Ciel tomorrow if he raced through the rest of the reports in the morning. Sebastian heard the sound of his tent zipper coming undone and he turned his head he saw Ciel once again standing before him. The neko’s presence was not entirely unexpected, Ciel had a habit of showing up unexpectedly and it had been how most, if not all, of their encounters had started, what was unexpected however, was the very dead mouse hanging from Ciel’s mouth. It was around the size of one’s hand and had a light grey striped coat, but didn’t appear to be covered in blood as one might expect.

“Ciel?!” Sebastian stood up and frowned. He had intimately kissed that mouth and now it held a dead animal inside of it. There was something so much worse about a dead rat as opposed to a fish, perhaps it was the idea that mice were diseased and that fish, being always in the ocean, were cleaner from all the water. Whatever the case, Sebastian was hoping that this wasn’t another gift, he did not want to eat a mouse, no matter how smitten he was with Ciel.

The neko grabbed the dead animal from its holding place and handed it out to him “it’s fresh” he insisted, like that made it any better.  
“Sorry, but I’m not eating a mouse. Humans don’t eat raw mice” the scientist explained. The neko retracted his gift, eyes big in the low light of his study lamp, his ears flattened themselves against his head.  
“You’re my mate, giving you food shows that I love you” the neko looked like a kicked puppy and Sebastian found himself between a rock and a hard place.  
“You love me?”  
“Of course I do! I’ve been courting you for days” Ciel placed the mouse on the table, “you kept them?” he traced the slightly wilted blue petals with a gentle touch. The flowers had been carefully arranged in a large mug as there wasn’t anything else to put them in on the island.  
“Of course I kept them” the scientist used Ciel’s previous words “I… I love you too” he admitted and it felt like all the breath had been taken out of him. He found that he _did _love this creature, Ciel had barged his way into the scientist’s life and now he never wanted the neko to leave. The day had been torture thinking about Ciel, but not being able to see him.__

__“So you _do _want to be my mate?” the neko asked hopefully and grabbed the researcher’s hands with his own.__  
“You’d just be called my boyfriend in human language” he explained “I don’t know anything about what nekos do for… courting” Sebastian frowned.  
“I forgot that you’re so different to me, it was only really apparent last night”  
“Talking about last night, did you bring back my towel?”  
“You wanted it back” the neko flushed at that, remembering how he’d ruined it, went to his den and washed it, and then ruined it some more. He had needed something to do in between cat naps and looking for Sebastian, and the fabric had surprisingly retained much of the scientist’s scent…  
“It’s just a towel, I guess it doesn’t really matter” Sebastian brushed it off, thinking that Ciel had probably lost it. 

____

______“So you love me, and we’re… boyfriends” the scientist nodded “and you kept my flowers” the neko leaned into Sebastian’s chest and rested his head there, the scientist’s arms automatically encircling him.  
“Do you even know what they mean?” the cat man asked, eyes closing as he simply breathed in that unique Sebastian smell.  
“Humans give flowers to show that they care about one another, I don’t know if nekos have other meanings for them” he explained.  
“These flowers are special, they’re symbolic. You’d understand if I had been able to finish my performance yesterday, but the other humans barged in. My kind persuade our possible partners with mating displays and courting rituals”  
“The food, the flowers, all the lounging around seductively, were those your courting rituals?” the scientist asked, one hand idly playing with the nekos silky ear.  
“Yes, but there’s more I haven’t shown you…” Ciel pushed the man away slightly to look him in the eyes “you’ve never touched me” Ciel gestured to his lower half “and that’s not your fault, it was never the right time but… we’re not entirely the same”  
“What do you mean?” was Ciel not male? Did he have sex organs that would be completely incompatible with him? He knew next to nothing about this creature. 

____“Can you get rid of the brightness?” the neko asked, standing further away from him, and Sebastian flicked off the study lamp, throwing the tent into the darkness of night. He could just see Ciel move in the gloom, his eyes still slowly adjusting to the lack of light, but then an ethereal glow appeared slowly from the neko in front of him. His slit opened up, a soft electric blue light emitting from the blue skin and as Sebastian stared, not knowing what to make of it, a long protruding shape slowly emerged from the glowing opening. Ciel’s cock was a luminescent blue, it was longer than his own, but also thinner and grew a darker shade of blue towards the base. The prick was smooth and almost shiny with a small raised seam that wound around the member in a twisting coil, the slightly raised skin reached from the ridge of the head down to the base._ _ _ _

____“Wow, that is different” he didn’t know what to make of this thoroughly inhuman cock, it was certainly eye catching and he could see it being part of a complex mating ritual. But then something else happened that he had never seen before in nature, little blue tentacles, also bioluminescent and incredibly thin, pushed out of Ciel’s slit to spread softly around his cock. They stretched across his skin in an inviting display, almost like the petals of a flower…_ _ _ _

____Ciel was uncharacteristically nervous, while he had been proud of his display when the other nekos had still been around, his length and colour truly unique and desirable, he now felt afraid that his love wouldn’t like their vast differences. Sebastian did not glow, he had no lures, no natural slick, and his member rested outside of his body. How could the human possibly find him attractive._ _ _ _

____“Holy shit…” Sebastian breathed out. Ciel was something else, for every part of him that resembled a human, there was another part of him that was undeniably inhuman. He watched the display fan out, looking more like an exotic flower than anything else Sebastian recognised, they looked innocent and dainty in the darkness of the tent as the swaying tentacles softly probed around Ciel’s stomach and thighs, he couldn’t help being mesmerised by the unique and otherworldly sight._ _ _ _

______“Do you still love me” Ciel’s unusually timid voice broke the silence of the tent.  
“I’ve never seen anything like you before” the scientist came closer to the neko. Sebastian could see Ceil’s worried eyes as they reflected the soft blue light, he didn't want Ciel to be nervous or afraid.  
“I’m your mate, why would I stop loving you?” Sebastian closed his hand around the luminous prick and Ciel’s breath hitched. No one else had touched him since the other nekos had been around, and they had been gone for so long now, he felt that he might come undone from this simple touch alone. 

____The glowing member felt silky and warm, and it was doused in a natural lubricant that made his hand tingle with heat. Sebastian slowly moved down the cock, feeling the soft raised line that spiralled down the strange length, he couldn’t really understand its purpose, but the thin tentacles shivered when he reached the base and Ciel moaned when he squeezed lightly. The glowing light was partially blocked by his hand as he stroked the length, he couldn’t take his eyes off the unbelievable sight, “beautiful” Sebastian whispered._ _ _ _

____“Sebastian… please” the neko whined, eyes shut tight as he pushed forward for more friction. The researcher wrapped two hands around Ciel’s blue glowing member and started a steady rhythmic motion, the little feelers retracted, their mission to lure in a partner complete, and as the scientist stroked the length he felt the natural slick increase until the whole thing was dripping onto the floor of his tent. He wondered how much of it was pre-cum and how much was slick when the neko suddenly kissed him, his own hands coming to clutch at Sebastian’s ass, as if to hold on as he rocked into the scientist’s hands. Sebastian broke the kiss to kneel before his inhuman partner, he experimentally licked the tip and felt a pleasant tingling run across his tongue. The neko moaned again and he felt the member swell and expand in his hands “more” Ciel begged. He was a needy thing, but Sebastian obliged and took the head into his mouth, he rolled his tongue over the tip, tasting a strange sweet flavour that was similar, but wasn’t quite the same as human seed. Sebastian felt his own pants tighten in response and wished they had more privacy then his simple tent._ _ _ _

___It made him think of his apartment back in Melbourne, made him think of how the neko would look bundled up in his sweater and lounging on the sofa. He thought of how they could make hot chocolate, watch a movie, get bored and make out (which would inevitably lead to sex). What would happen after Sebastian left the island, what would happen to Ciel when the boat arrived and he had to go home. Would he take the neko with him?_ _ _

____He couldn’t think about that now, not when Ciel had his fingers buried in his hair and was moaning his name.  
“Sebastian…” the neko whispered breathlessly, and as he slowly slid up and down the luminescent cock he felt it twitch and lift upwards. Cum filled his mouth, he wasn’t expecting Ciel to release so soon, and especially without any warning, he swallowed what he could, but it just kept coming and he was forced to cough and sputter as white ropes spilled across the tent floor (fuck this would be hard to clean up). But the sheer bliss on his strange island lover’s face was enough for him to ignore the mess. _ _ _ _

The neko after finally finishing pushed Sebastian onto the tent floor, he franticly kissed the scientist, rough tongue diving into the man's mouth as his still hard cock rubbed against Sebastian own covered one. There was something about ingesting Ciel’s slick that had set his blood on fire, his scientific mind wondered what chemicals were inside the natural lube to incite this kind of reaction from his body, whilst the rest of him simply wanted Ciel to grind his hips against his own _harder _and worry about scientifically understanding the world later. Sebastian released quickly in his own pants and only then finally did Ciel’s hard glowing member soften and retract back inside of him.__

____

______All Sebastian could do was pant and try to catch his breath as he sat uncomfortably in his now very damp pants, pinned down by the purring neko. Ciel nuzzled into his neck, desperate for more closeness, there were no pesky humans to break them apart this time so he enjoyed listening to the still fast beating of his human’s heart. Sebastian, after a moment of simply coming back to the world, reluctantly sat them upright._ _ _ _ _ _

______“Let me clean up and you can stay with me in my sleeping bag tonight” at the scientist’s words Ciel got up to allow him to stand, strip and wipe them down with a damp towel (using water from the half empty bottle on his desk).  
“Over here” Sebastian climbed into the polyester bag and lifted up the side, he didn’t bother to dressing himself in pyjamas (it's too hot anyway), or zipping up the sleeping bag when Ciel wormed his way inside, there was no way they would both fit if he did. The neko’s tails wrapped around his bare leg and Ciel rested his head on the slightly taller man’s chest, content purring rumbles emanated from him and Sebastian melted at the sound, further enamoured with the precious creature that had stolen his heart. All of Ciel’s worry had melted away, his mate still cared about him despite their differences, and he couldn’t be happier._ _ _ _ _ _

__________Sebastian never expected the unusual display Ciel had shown him, he couldn’t have predicted that this creature so human like in his appearance could have such bizarre adaptations between his legs.  
“How did you know which tent was mine?” Sebastian asked instead of all the other questions running around in his head.  
“This den smelt like you” Ciel responded simply, their arms were wound around each other, legs tangled and heat shared. Sebastian felt like he was in heaven. 

______“What happens when I leave…” he didn’t want to ask Ciel about this, didn’t want to think about it let alone talk about the inevitable end. But it would be cruel to pretend that Sebastian didn’t already have a plane ticket booked for a domestic Sydney to Melbourne flight in three weeks. The neko shuffled to look him in the eye, his duel coloured orbs reflecting what little light fell through the tent’s fabric.  
“You can’t leave me, I’ve never had a lifelong mate before, but I think you could be the one… can’t you stay here on the island, I’ll take good care of you” Ciel begged. He doesn’t want this to end, he can’t go back to being so lonely. If Sebastian leaves, he knows that he’ll give up too and join his brothers and sisters in the jungle as a mindless insignificant cat._ _ _ _ _ _

______“You’re not human, and I can’t stay here, I don’t know how to get you off the island. Everything’s on lockdown because of the research being done here” Sebastian explained, and he wished that the light was worse so that he couldn’t see Ceil’s eyes water.  
“I love you, but I won’t force you to be with me” it hurt to say, he had never been so attracted to anyone else before, but Ceil couldn’t control Sebastian. The scientist tightened his hold on the neko “I’ll work something out, I’m gonna find a way to take you with me” Sebastian promised “I don't think I can leave you behind…”_ _ _ _ _ _


	5. Documentation

**Summary for the Chapter:**

> A good scientist should properly document their discoveries

**Notes for the Chapter:**

> This would have been up sooner, but I got distracted drawing fanart of mouse!Ciel and cat!Sebastian, my friend Demonofphantomhive drew some more amazing art for my fic on tumblr!  
> https://secretly-a-wuss.tumblr.com/post/175316890558/demonofphantomhive-sebastians-got-a-lot-on-his (Seb with a lot on his mind)  
> https://secretly-a-wuss.tumblr.com/post/175352936148/demonofphantomhive-since-i-drew-neko-sebastian (Seb if he were a neko)  
> They're amazing, and I love them!

Light and dainty fingers tipped with grey claws trailed over a toned chest. The neko breathed in his human’s delectable scent and felt arousal stir inside him, while the attention he had received last night was wonderful, (Sebastian’s touch soft and inquisitive, yet still frim enough to bring him to completion) the lust that still stirred within him simply required _more _. The neko fought his body for control and was able to mute his desire to avoid ruining this perfect morning by prodding his mate awake with his lust, a truly skilled neko could control their cock almost absolutely, and Ciel had nothing but time on this island to learn control. Sebastian deserved a peaceful undisturbed sleep.__

__Even though Ciel tended to prefer many short naps throughout the day over sleeping for the whole night, he couldn’t bring himself to leave the strange warm nest. The odd smooth textured wrap that covered them carried Sebastian’s smell despite being so strange, so he tolerated it. The real reward was to be able to gaze upon his sleeping beauty close up. He had been so worried that Sebastian would not like him as a mate due to their differences, but thankfully that hadn’t been an issue._ _

__Ciel couldn’t stop the joyful purrs that rumbled deep in his chest, he loved everything about his mate, loved Sebastian’s soft black hair, and his stunning eyes and even his voice that was somehow beautiful as well, the neko could listen to him talk all day. Ciel sighed, he would have to leave soon, already he could hear some of the other humans waking up in their nearby dens. With a loving kiss to his mate’s forehead Ciel slipped out of the man’s hold, untangled his tails from their legs and left behind his beloved._ _

__\--_ _

__Entomologist Claude Faustus exited his own tent hoping to get into the shower tent early when he spotted the most peculiar sight. His fellow scientist Sebastian Michaelis had just chucked out what appeared to be a dead mouse from the door his tent. The other scientist frowned, what would Michaelis be doing with a dead animal? There had been rumours that he was having an affair with one of the other scientists, relationships between staff being against the university’s policy, but Claude couldn’t work out how what he was seeing now connected to those rumours. Maybe Michaelis was just a weirdo? The scientist shook his head, it wasn’t really his business, so long as Michaelis wasn’t breaking the rules imposed on them by the research board it didn’t really matter._ _

__\--_ _

__“Australia’s great, human technology is far beyond anything you have here, you’d be amazed” Sebastian explained as he scanned the canopy with his gaze, hoping to see the new species of bird the team wanted better photos of. It was supposed to have brilliant red feathers with a serrated curved beak, it was quite an unusual species. Ciel had said that the birds liked to stay up high in the trees to cut open the tough fruits up there with their sharp mouths, so with his help Sebastian was searching the areas the neko had seen the birds frequently appear in. The team had taken to calling them grells because of some convoluted reasoning the other scientists had been talking about, Sebastian didn’t really know why, nor did he care to listen to their explanation, he had been too busy doodling pictures of Ciel in his ‘scientific’ journal._ _

__Ciel merely tilted his head, he couldn’t imagine life _not _on the island.__  
“I don’t really have anything here for me anymore…” the neko softly held onto the short sleeve of the scientist’s shirt “I miss my own kind, we would have had a big celebration for the success of our courtship. There’d have been so much prey already caught to eat, and wrestling? I think it would be called…” Ciel wasn’t sure how best to describe the play fighting that occurred during celebrations, there wasn’t really a word for it in Sebastian’s human tongue.  
“you would have enjoyed it, I could have shown you off to my parents” Ciel’s ears lowered and lay flat against his head, displaying the sadness in his tone. 

____

“Ciel…” Sebastian cupped the sombre neko’s face with his hands, he didn’t really know how to comfort his love, there was no way to bring back his fellow nekos.  
“If I work out how to get you off this island, then I’ll introduce you to _my _parents, I bet they’d love you, you’re adorable” the scientist squished Ciel’s cheeks earning himself an annoyed whine and a glare that just made the neko cuter. From the small smile that Ciel tried to cover up Sebastian knew that he wasn’t really upset with him, the scientist released his cute face after kissing him on the nose and they continued to look for the elusive birds together.__

____

__________The couple talked about human and neko culture for what seemed like hours, talking about their lives before they met each other, when Sebastian eventually did find the birds he was looking for. The scientist stopped to photograph them and record their behaviour.  
“So, it’s your job to take photos of all the things that live here?” the neko asked while lazily sharpening his claws on a nearby tree.  
“That’s part of it, were also hoping to learn about their behaviours and gather information about population size and biodiversity levels. The research department want to see if pollution has had any effects on the animals here, so were checking a lot of the fish near the shore for microplastic” the zoologist explained.  
“I only understood about half of that” the neko grew board of scratching the tree and took to digging through Sebastian’s backpack instead.  
“You could do distance education if you came home with me, you’re clearly highly intelligent” the scientist shrugged off his bag to let the neko look through it properly. 

______Ciel curiously picked up and sniffed an apple Sebastian had packed for lunch before he quickly put it back when he deemed it boring, instead he pulled out a stack of documents with little photos attached to them._ _ _ _ _ _

______“You have pictures of all the prey here…but you don’t have any of me” the neko’s pupils narrowed, predatory slits watching the scientist with hunger. The neko ran his hands down his body suggestively, playing with the soft skin of his own abdomen and creeping lower, he decided that Sebastian had done enough of his boring human work for the day. With an elegant sway of his long soft tails, he captured the attention of his prey…  
“Hey mister science human, don’t you need to photograph me?” he asked playfully as his blue member started to peek out of his slit. Sebastian couldn’t stop himself from grinning and shaking his head at Ciel’s words, the neko loved playing games. Ciel liked his lips, wrapping his tongue around a finger before he brought it into his mouth to suck on lewdly._ _ _ _ _ _

______The neko closed his eyes as he moaned exaggeratedly and stroked his rising erection. Sebastian couldn’t really see the bioluminescent glow in the afternoon sun, but the striking blue flesh still looked stunning, Ciel’s hand couldn’t cover it all as he softly stroked up and down the length. Sebastian raised the high quality scientific camera to play along with Ciel’s game, the neko posed for him, tails curled around his legs in pleasure as he leaned against a tree for support. The humanoid cat creature sunk to the ground, legs spread as he raised both hands above his head and rutted into the air, his fully hard cock dripping and needy at the lack of friction. He turned his face away as if ashamed, but the evil smirk on his lips betrayed the excitement and pleasure the neko got from displaying himself before his mate. As Sebastian photographed it all he felt his own pants tighten, the adorable kitten had turned into a sultry predator, ensnaring his prey with a burning look that promised pleasure._ _ _ _ _ _

______“Fuck, Ciel you’re so beautiful…” the scientist breathed out as he palmed the front of his shorts, it was too hot on the island to wear anything longer even though he preferred full length pants.  
“Oh Sebastian, touch me” Ciel whined, clawed fingers buried in his slate blue locks, lures fully extended at the prolonged teasing. The little aqua blue tentacles writhed with pent up energy, they should have been strange, alien even, but Sebastian though they looked like the petals of a flower, elegant and otherworldly. There was something hypnotic about Ciel that demanded his full attention, not that he’d want to look away. _ _ _ _ _ _

______Still holding the camera, the scientist reached out a hand to wrap around Ciel’s burning flesh, he photographed the explicit pose, his black nailed fingers wrapped around the stiff blue flesh. Sebastian’s hand was quickly drenched in the odd tingling slick, but in the light of day he could see the white fluid dribbling down Ciel’s length clearly as it mixed with the transparent lube. He thumbed the tip, pressing into the small slit there as he took photos of Ciel’s ecstasy, the neko moaned as Sebastian stroked him, hips undulating and rocking into the soft human hand as his eyes fluttered, torn between watching or just laying back and enjoying the act._ _ _ _ _ _

The scientist gave up taking pictures and carefully placed the camera on the ground before he dropped it. Sebastian struggled to unbutton and unzip his pants with one hand (the other still occupied) when his radio suddenly sounded, _“attention all members of staff, the celebratory dinner will be held in 1 hour, please return to the campsite immediately to prepare” _a little voice whined through his handheld radio and he cursed everyone in the research team. Ciel hissed at the small machine as it made his mate pull away and let go of his need.  
“I’ve got to go…” the scientist announced disappointingly “it’s gonna take me at least an hour to get back, and I still have to change clothes” __

____

________Ciel frowned, not happy at all with this turn of events, he wanted Sebastian and he wanted him _now _.  
“I wanna fill you so bad” the neko captured his lips in an unexpected kiss, tasting the inside of his mouth before he released him to look sadly at his lover “I wanna fuck you, want you to be happy, want you to be mine… properly” the cat man licked his lips as if savouring the taste of his human. Sebastian could only nod dumbly as he felt his cheeks redden, there was something about saying dirty things that was far more lewd than actually doing them. He didn’t know if he truly wanted Ciel to take him with his strange non-human cock, but before he could find his voice again the neko had already disappeared into the dark of the forest.___ _ _ _ _ _ _ _

__________\--_ _ _ _ _ _ _ _ _ _

__________The head scientist William T. Spears had decided that the camp needed a boost in moral to ensure productivity and so they were hosting a mandatory staff dinner to celebrate the successful week of research that had concluded without any issues, incidents or setbacks. Sebastian hated the event, not only did it cut his time short with Ciel, but he felt like it was somehow tempting fate, like they’d all be jinxed and _everything _would go horribly wrong in the next week.___ _ _ _ _ _ _ _ _ _

____________Sebastian sipped on his cold drink from the ice box and wondered what Ciel was doing now, would he be mad at his abrupt exit? It wasn’t very polite to leave someone in such a state, on the edge with no release… He was sure that the neko would find a way to get back at him the next time they were together._ _ _ _ _ _ _ _ _ _ _ _

______________________“Mr Michaelis?” Sebastian turned around, Claude Faustus the creep from the insect research division called to him. He didn’t know much about Faustus, he knew that they looked similar and that Claude specialised in entomology and had a strange passion for spiders, he was often silent and emotionless leaving him with few friends within the research team. Claude was a bit of a loner, dedicated to his work, but too odd to be close friends with the anyone in the team.  
“Can I help you?” Sebastian raised an eyebrow, what could the other scientist possibly want from him?  
“I noticed something peculiar this morning, you threw out a dead rat?”  
“Uh” the scientist stalled unintelligently. Fuck, he didn’t think anyone would have noticed, he’d spent only a handful of seconds tossing Ciel’s ‘gift’ out the door of his tent. 

____________Sebastian feigned ignorance “I don’t know what you’re talking about?” It was a weak lie and he knew it. Claude’s face had remined unreadable, like a blank slate, for the entirety of their conversation, the entomologist was obviously still suspicious about the incident and Sebastian couldn’t blame him, but he couldn’t think of a single excuse in that moment that Faustus might actually believe, best to just play dumb, deny everything. The scientist wished that he was with Ciel right now rather than stuck in this noisy, stuffy and hot cafeteria tent that the higher ups had forced them into. Claude shrugged as though it wasn’t any of his business and walked off much to Sebastian’s relief, but Sebastian’s nervous reaction did raise a stronger curiosity within Claude, what could Michaelis possibly be hiding?_ _ _ _ _ _ _ _ _ _ _ _

____________Sebastian sighed and downed his now lukewarm drink in one go, he left the makeshift party tent and slipped out. He didn’t feel like talking to any of the other researchers, he just wanted to go to sleep. The zoologist entertained the thought that maybe Ciel would visit him again in the night, but dismissed it quickly, the neko probably wouldn’t think it safe to enter the camp with most of the staff staying up late because of the party._ _ _ _ _ _ _ _ _ _ _ _

He couldn’t stop thinking about what Ciel had said, and as he looked over all the pictures they took today and put them in a folder hidden away in his personal documents (in between a folder containing pictures of his cats and his old Yuri on Ice fanfiction), Sebastian sighed again, wishing that he’d been able to give Ciel a better response. He was honestly a little frightened at the thought of being fucked by something that wasn’t human, even though they were both able to consent and communicate it still made him nervous, he didn’t know if Ciel’s bioluminescent dick was even safe to use down there. It wasn’t his first time being on the bottom, but what if being with Ciel ended up hurting him? Perhaps it would be safer for him to top first and then they’d see how they went from there. Sebastian couldn’t lie to himself though, he wanted Ciel just as much, and in _every _way…__

____

______________\--_ _ _ _ _ _ _ _ _ _ _ _ _ _

____

______________Sebastian woke with a start, he couldn’t remember drifting off, but somehow knew immediately that this wasn’t his tent. He was lying on his front and the first thing he noticed was the dark, his vision was blocked by some kind of cloth tied around his head, and when he tried to move his limbs he found his hands tied together above his head and his legs spread apart, some kind of rope tied around each ankle. An experimental pull revealed that the binding was fairly strong.  
“Hello?” he called out, glad that he hadn’t been gagged as well “what’s going on?” his voiced echoed in the dark and that’s when he felt claws lightly trail down his back._ _ _ _ _ _ _ _ _ _ _ _ _ _

____


	6. Chemicals

**Summary for the Chapter:**

> Sebastian finds himself naked, blindfolded and tied up in a cave...

**Notes for the Chapter:**

> For everyone who's read this thank you so much, all the support, kudos and comments I've received have blown me away.
> 
> Sorry this has taken longer to come out than the other chapters, I've been busy making black butler art on my tumblr @secretly-a-wuss, I also have a new story called Butler to an Octopus, which is gonna be fluffy af

“Ciel… did you kidnap me?” the scientist’s concerned voice echoed around him and he deduced that they must be in a cave of some sort. How did the neko take him without anyone noticing, where were they, why was he blindfolded and tied up? As his mind raced a hungry mouth littered the back of his neck in messy kisses causing sharp fangs to occasionally graze his skin. His hips were yanked upwards forcing him onto his knees and elbows “Ciel-” the neko’s clawed hand wrapped around his growing erection and any complaints he might have had were silenced by Ciel’s ministrations.

“Shhh” the neko whispered in Sebastian’s ear, his own body draped over his tied up prey.  
“My little human... I’ve been waiting for so long to fuck you...” the neko purred and the pure desire in Ciel’s voice made him shiver.  
“I adore you, whenever we’re apart you’re all I can think about, I just want to stay with you forever” the cat babbled, grinding his own excited member against Sebastian’s ass. The scientist was completely devoid of clothes and seemed to have been placed on some sort of moss bed. 

“Do you want me too?” the neko whined. The slick from his glowing member set Sebastian’s skin on fire, he wished he could see, wished he could touch Ciel as well, but the neko pulled away, hands cruelly leaving his need. His ‘abductor’ yanked off his blindfold to reveal a cave lit up by tiny twinkling lights, it looked like someone had taken the night sky and hid it underground.  
“Glowing worms” Ciel explained as Sebastian took in the view “they are not prey, they’re no good to eat”

The cave was filled with them, bioluminescent glow worms tied to the walls and the ceiling. The backdrop of gorgeous tiny lights only enhanced Ciel’s appearance, and with his blindfold removed he could now properly take in the almost magical sight of his neko boyfriend. One eye glowed a stunning blue, the same shade as his excited member and the little petal like tentacles that surrounded his inhuman cock, while the other eye burned a sultry violet. His pupils were narrowed, despite the dim lighting, and Sebastian felt like a mouse, stripped bare and bound before Ciel. He was completely at this creature’s mercy.

The half cat stood in front of him, arousal displayed like a blooming flower. Ciel wrapped a hand around his length and teasingly dragged it up and down, the vibrant blue glow grew brighter every time he reached the tip and faded as he made his way down to the base. Like the flashing of a firefly, Ciel lured in his mate with a mesmerising display of bioluminescence.  
“I want you so much Sebastian” he breathed out shakily, the only thing that glowed brighter than Ciel’s cock seemed to be his duel coloured eyes that reflected all the light in the cave and were focused solely on the scientist. The neko was waiting for his answer, he would not hurt his precious human, would not do anything Sebastian didn’t want him to.

But could Sebastian really take that step with Ciel, what about his pledge as a scientist, they were supposed to discover new life not fuck it. However, Ciel’s bioluminescence was stunning, the dancing light that timed itself to the lazy playful strokes of Ciel’s hand was somehow alluring. He found that he _did _want the neko, wanted more of that bizarre cock that constantly surprised him. Scientists were supposed to discover things after all, and he was nowhere near finished exploring the creature he had fallen head over heels for.__

__“I want you... Ciel, I love you” Sebastian admitted. He may have been scared, waking up naked and tied up in a cave wasn’t exactly normal, but he trusted Ciel, he knew that he wanted nothing more than to be with him._ _

“Sebastian...” the neko kneeled down and held his face adoringly. And although the only real light in the cave came from the neko’s bioluminescence and the glow worms dotted around the cave, the pure love on Ciel’s features shone through regardless. “I won’t hurt you, if you tell me to stop at any time, I’ll stop” Ciel kissed his lips and Sebastian could feel the neko smile against his mouth. “Are you gonna take these off as well?” he asked when they parted, referring to the odd homemade rope that while soft, still restricted the movement of his legs and arms. The rope holding him seemed to be made of dried vines braided together, and it had some kind of soft material woven in where it wrapped around his arms and ankles, preventing it from digging into his skin too much. 

__“Now why would I do that, you look so pretty all tied up” the neko grinned revealing his sharp feline teeth “I spent so much time planning this, I had to get you away from those pesky humans so that we could be alone… Just enjoy yourself” Ciel purred as he moved to position himself behind the scientist. Clawed hands drifted lovingly down Sebastian’s back before resting on his cheeks to pull them apart. The scientist gasped as a wet hot tongue licked a line up his taint, the neko’s tongue traced the outside of his little hole before Ciel dipped the slightly rough muscle inside. He started up a rhythm devouring Sebastian, tasting and licking, which quickly had the scientist pushing back against that hot and hungry mouth._ _

Ciel stoked himself and gathered up some of the natural lube that coated his glowing cock, he pushed a single finger inside drawing a quick intake of breath from his mate. Ciel’s slick always made his skin tingle, but to have it coating his insides set Sebastian on fire in the best of ways. The neko curled his finger, looking for that sweet spot inside of his partner that would make him _really _moan. And when he brushed against it, Sebastian swore.  
“There” he whispered, Ciel rubbed the same spot again and knew it was what he was searching for by the wonderful sounds Sebastian made. __

____He grabbed his blue glowing cock and eagerly guided it towards Sebastian’s entrance “wait, shouldn’t you- ahhh fuck” he swore again as Ciel pushed the tip of his cock inside. Somehow it didn’t burn painfully like Sebastian thought it would, the neko’s member had become thin so that it could easily slip inside, and Ciel whined like an animal as he pushed in the rest of the way until he was buried to the hilt, soft tentacles brushing against Sebastian’s rear. He pulled out slowly and thrusted in a bit faster as he started up a steady rhythm, not bothering to wait for the scientist to get used to it since Ciel wasn’t very thick. In fact, Ciel seemed even smaller than the other times they had messed around, and Sebastian found himself a little disappointed, he thought the neko would be... better._ _ _ _

____But then something unexpected happened, as was often the case with his inhuman boyfriend. Ciel’s member expanded inside of him, the cock grew thicker and longer, stretching him perfectly as Ciel picked up speed. The slightly raised spiral along the length only added to the scientist’s pleasure, and Sebastian moaned as his inhuman partner hit his sweet spot with alarming accuracy, his own untouched length dripping already as he ached to stroke himself. Thick strands of slick connected and broke between them, and Sebastian was quickly drenched with Ciel’s lube, perhaps overly so, but it made everything feel so much more sensitive._ _ _ _

____“You’re so tight Sebastian” Ciel moaned and hissed as his tails curled in pleasure. At that moment, when Sebastian’s knees grew wobbly and the neko’s claws dug into his hips, Ciel knew that this human was the one. Sebastian would be his lifelong partner, they would raise kittens together, grow old together, live forever on this once so terribly lonely island. The neko decided that the human had adjusted enough so he didn’t hold back anymore and set a brutal pace with his now considerably large cock, that had the scientist panting and whining in pleasure. Ciel knew that he’d never be lonely again, he’d show Sebastian that he was the perfect mate for him._ _ _ _

____Sebastian couldn’t even think straight, but concluded that there must have some kind of crazy evolutionary sexual arms race to have the most overly complicated reproductive organs. That was the only explanation for the neko’s strange biology that now included a cock that could presumably expand to fit any hole. Add in the tentacles, bioluminescence and natural lube and you had one overly elaborate dick design._ _ _ _

“Fuck… Ciel!” he whined as he felt the cock grow just that tiny bit more as it stuffed his hole, the huge length absolutely wrecked Sebastian in an attempt to show the neko’s devotion. Ciel leaned over him, never slowing down as he grabbed hold of one of the human’s hands. He bit down on Sebastian’s shoulder which strangely didn’t hurt, even as he felt blood run down his skin. In fact nothing hurt and he fuzzily concluded that it must have been because of Ciel’s natural lube, _was it a painkiller too?_

______The half cat lapped up the spilt blood from the bite, but then forced his chest into the moss bed, changing up the angle and drawing yet more beautiful moans from his love. Sebastian felt drool gather at the corner of his mouth as he was utterly ruined by Ciel, he didn’t know how much more he could take, but then Ciel was pulling out and tearing through the ropes around his legs to flip the man over with an unusual display of strength._ _ _ _ _ _

______Sebastian could tell form Ciel’s face that it was nowhere near over, lust filled his fluorescently glowing eyes that held narrowed catlike pupils. They were tied to him like the moon to the earth as Ciel’s electric blue glowing cock hung heavily between his legs, it was far larger than the other times he had seen it and he couldn’t believe that all of it had been inside of him. Nothing seemed real in the dark of the cave, and when he thought about it all he could feel was pleasure. He felt no cold despite not wearing clothes, he felt no pain from the bites, nicks and scrapes of Ciel’s fangs and claws, and the burning stretch that he would have expected from a cock of that size was pleasantly absent. He felt so heavy, but so free at the same time and his head was pleasantly blurry._ _ _ _ _ _

______The neko stole his breath away with a desperate hunger filled kiss, fangs nicking the man’s lips as he pushed the scientist’s legs up and apart, and drove into him again. This wasn’t like the other times they had been together, Ciel wasn’t holding back now…_ _ _ _ _ _

______“You’re not gonna be able to walk after I’ve finished with you...” Ciel promised as he bathed his neck and shoulders in rough passionate kisses. The neko fucked him harder, worshiping his body with greedy kisses and groping hands, Ciel whispered dirty things that had Sebastian thankful he was now lying on his back, as he didn’t think his legs would have been able to hold him up._ _ _ _ _ _

Sebastian felt like he was on drugs, his vision swam and the dainty lights in the cave became blurred bluish white colours, all he could feel was a numbing pleasure and the only thing he could _really _see was those duel coloured eyes that never faded or went out of focus. He tried to say something to Ciel, but his tongue tripped over itself as another forceful slam of the neko's hips made him forgot the words he was going to say. He felt like his arms should have hurt, they were still tied above his head but he couldn’t remember why they didn’t feel like anything. All he could feel was Ciel’s fluorescent cock as it pounded into him, and in his drug affected mind he _worshipped _that dick, wanted to go home and build a little shrine for it if it meant he’d feel like this all the time. Especially as the huge stiff length worked him into a pleasure filled puddle of mush.____

_____ _

__________Strange abnormally hot seed filled his insides and his own pleasure peaked as Sebastian came violently, spraying ribbons of white over his own chest, the feeling blinded him for a moment and he wasn’t sure if he had blacked out or not. Couldn’t be certain of anything other than the mess of slick and cum that dripped down his ass and made the moss bed damp (well, damper, as he had already ruined it with all the sweat from his overused body). The scientist giggled weakly, a drowsy smile aimed at the stunning purple and blue orbs that stood out sharply against the night sky behind them._ _ _ _ _ _ _ _ _ _

__________“I’m not done with you yet” the eyes growled, claws digging into his thighs as they were pushed further away to give the neko more access. They drew little beads of blood, but Sebastian didn’t notice, too busy trying (and failing) to recover from his orgasm. The duel coloured eyes eagerly cleaned him out with a burning tongue and an impatient mouth, and Sebastian gasped and whined at the neko’s unrelenting attention. A name came to his mind that was drowning in pleasure, and he desperately clutched the tiny bit of information to him as he felt his vision darken before coming back too sharp and too bright.  
“Ciel…” he moaned, eyes squeezed shut. He wasn’t sure he could move even if he wanted to. _ _ _ _ _ _ _ _ _ _

__________“I love you Sebastian” a beautiful voice told him reassuringly. A hand might have cupped his cheek, or it might have been the tears he felt streaming down his face as the neko lined up with him yet again…_ _ _ _ _ _ _ _ _ _

__________\--_ _ _ _ _ _ _ _ _ _

__________Sebastian blearily opened his crimson eyes to see the dimly lit walls of a cave. Sunlight peeked through the cave ceiling from cracks at the top, this chamber was smaller than the last, or at least it felt smaller, he could also hear running water, which he hadn't heard earlier. Pain raced upwards from his rear, not as much as he would have expected, but still enough to make him groan, which didn’t help since his throat was dry and sore as well. His skin also burned where his neko partner had accidentally scratched him (or at least he hoped it had been accidental). He didn’t remember blacking out, instead all he could remember was a seemingly endless pleasure the likes of which he’d never experienced before, like some sort of fever dream._ _ _ _ _ _ _ _ _ _

__________“Sebastian!” the neko cried. Duel coloured eyes full of worry filled his vision as hesitant hands cupped his face, almost as though he was made out of glass and would break if Ciel was too rough.  
“I was so worried when you wouldn’t wake up” Ciel’s pointed fuzzy ears lay pressed against his head as he teared up, little sobs making their way through the half cat’s lips despite him trying to cover Sebastian’s face in gentle kisses._ _ _ _ _ _ _ _ _ _

With a momentous effort he raised a hand to stroke the back of Ciel’s head, and from the neko’s puffy eyes and tear stained cheeks he could tell this wasn’t the first time Ciel had cried.   
“Hey, don’t cry. I’m fine, just a little exhausted” he smiled wearily at the neko in an attempt to put him at ease. But Ciel merely shook his head and rested it underneath the scientist’s chin.  
“Neko slick makes love really good, but you’re not a neko… what if it had killed you, or done you harm. I didn’t think about the consequences”  
“I was okay when we were in my tent?” the scientist frowned.  
“Different slick… we weren’t mating then” Ciel explained as he traced soft circles around yet another bite, this one near his collar bone. 

After a moment of silence Sebastian had to ask, “what happened?” Ciel tensed, but quickly forced himself to relax, he hadn’t meant to hurt Sebastian and he had already spent enough time beating himself up about it.  
“I… got carried away” the neko blushed, “you were just so good and I was so excited to be with you!” Ciel nervously kneaded the scientist’s chest with his free hand, the other wrapped around Sebastian’s wait.  
“It’s not unusual for nekos to love all night, but you went limp and blacked out before sunrise” the neko’s voice broke as a fresh wave of tears flowed down his cheeks “I was so scared! I should have realised that the slick had affected you long before that point, and you wouldn’t wake up…” Ciel held Sebastian tighter “I thought I’d broken you!”  
“Hey” Sebastian ran his fingers through the neko’s soft hair “it’s alright. I’m alright. You didn’t mean to, you didn’t know that would happen” 

__________“I almost took you back to the humans…” Ciel’s tails wound themselves around the scientist’s leg as he tried to press himself as close as possible to his human. Sebastian couldn’t be mad at the neko, he had consented to it and honestly, despite being accidentally drugged and blacking out it had been one of the best experiences in his life. Sebastian wanted to know just what was inside neko slick that could cause such a strong reaction, he’d have to record his findings and do more research when he got back to his tent._ _ _ _ _ _ _ _ _ _

__________“Someone’s probably noticed that I’ve disappeared” Ciel didn’t respond, and the pleasant hazy feeling that had flooded his senses was overridden by a sense of panic at the possible repercussions. How long had he been away, what time was it, were there already search teams looking for him? All he knew was that he couldn’t let anyone else find Ciel, what if they locked him up and experimented on the neko, there was no way to ensure Ciel’s safety. He held his love tighter despite the tiredness in his limbs and was comforted by the soft purring rumbling in the neko’s chest._ _ _ _ _ _ _ _ _ _

__________\--_ _ _ _ _ _ _ _ _ _

Ciel had spent several hours trying to take care of his mate. Before Sebastian had awoken he had cleaned up the many claw marks and bites that littered Sebastian’s body, a frown was thrown at the slight red lines around the human's wrists but there wasn't much the neko could do about them, Ciel then wiped down the sweaty skin, spilt blood, slick and seed (they would bath when his human woke up). After that Ciel changed the bedding to soft new moss and periodically checked Sebastian’s heartbeat and breathing in an attempt to diminish his guilt and distress. He had hunted some cave mice and scrounged up a few edible berries in case Sebastian didn’t want any mice like last time, but couldn’t stomach eating himself, not when he had potentially injured his mate. He had been a fool to be so rough with his new partner and would do _anything _to make up for his stupid mistake, he had just been so excited and wanted to prove how good he was...__

____

____________And so Ciel had done everything he could think off, but the guilt he felt when he properly looked at the red claw and bite marks on that once unblemished flesh twisted his insides and brought fresh tears to his eyes. The neko could only catch a few minutes of shallow distressed sleep whilst he waited, arms wrapped around his human and head underneath the man’s neck, hoping that he’d wake up soon. He had spent a few uncomfortable and restless hours in this position trying to sleep, but ultimately ended up focusing too much on the human’s breathing and heartbeat to properly slumber._ _ _ _ _ _ _ _ _ _ _ _

____

When Sebastian finally did awaken relief and glee surged through Ciel. Although his human was a little confused (his pupils were still heavily dilated, proving that the slick had yet to wear off completely) he was _okay _and that was the most important thing. He also wasn't upset with the neko, despite having every right to be, and Ciel was glad that he wasn't chased off by the human for his reckless actions.__

______ _ _

______________“Sebastian…” the neko purred happily, soft ears tickling the scientist’s chin where it was tucked underneath “please don’t leave me again, I’ll be gentle next time” the neko snuggled in closer and Sebastian held him tightly in response. Sebastian rubbed small circles on the neko’s back and gazed half heartedly at the small handful of twinkling glow worms that sporadically littered the smaller cave. There were less here than in the previous larger cave, and they didn’t shine as brightly in the dim light of the cave, but it didn't matter, Ciel was the only thing he really wanted to look at._ _ _ _ _ _ _ _ _ _ _ _ _ _

______ _ _

______________The scientist’s only worry was that they were enjoying borrowed time._ _ _ _ _ _ _ _ _ _ _ _ _ _

______ _ _

**Notes for the Chapter:**

> (Glow worms are real animals, I went to a cave in New Zealand that was filled with them and they’re super cool)


	7. Data Retrieval

**Summary for the Chapter:**

> After over 24 hours of radio silence the research team at Toboso Island launch a search and rescue team to find their fellow scientist Sebastian Michaelis.

**Notes for the Chapter:**

> Sorry for the long wait, I've been busy with life and writing/drawing for other AUs, you can see what I've been up to on my tumblr blog @secretly-a-wuss if you're not already following me

Claude turned on the missing scientist’s computer, while the rest of the camp were forming search parties and making plans in an attempt to find Michaelis, the yellow eyed man was snooping through the scientist’s belongings in an attempt to work out where he could have gone. Sebastian hadn’t taken his radio and they hadn’t heard or seen from him since the camp party over 24 hours ago. He knew it was incredibly rude to look through another’s personal artefacts and invade their privacy, but they needed to find him quickly, or else they might be bringing a body bag home. 

The computer turned on, it’s screen loading to reveal a wallpaper of a dozen kittens tumbling across the background. The cursor flashed over the password box and Claude frowned, he didn’t know Sebastian well enough to be able to guess his password, he’s barely spoken with the other man. Claude looked around the tent, noting the scientist’s scattered cat themed pyjamas and abandoned paw covered coffee mug, before looking back at the screen. 

He typed in ‘cat’ only to receive an ‘incorrect password’ message in red text. He tried ‘cat lover’ and it was about as effective as before. ‘Kittens’ didn’t reveal any progress, and Claude started to worry that the computer might lock him out of he got the next one wrong… 

‘Ilovecats’

The computer opened up to yet another obnoxious cat background, this time of a cat sitting in a square glass container with text reading ‘cat loaf’ above it. Claude rolled his eyes before finding Sebastian’s most recently opened documents and scrolling through the list. Most of them were fairly plain and expected such as ‘Toboso island research and investigation doc 3’, there were also several unorganised pictures of native Toboso wildlife, however, one folder stood out in particular. It was simply marked with a leftwards facing arrow, also known as a ‘less than’ symbol in mathematics, and the number 3. For a while Claude didn’t know what the symbols were supposed to mean until he realised that it made a heart shape.

_This man is ridiculous ___

__Claude opened the file and his eyes widened in disbelief at what he found…_ _

__\--_ _

__Sebastian kissed the neko on his full pink lips, welcoming the nip of sharp fangs and Ciel’s rough tongue. The half cat guided him deeper into the spring, their chests dipping below the water as the refreshing liquid washed over all the nicks and cuts left behind by Ciel on Sebastian’s body._ _

__The drug like slick had finally worn off and Sebastian was left feeling sore and achy despite Ciel’s overbearing aftercare. The neko had fed him freshly foraged berries, cleaned his small wounds and massaged his sore muscles, but the scientist was in dire need of a real bed and a proper meal, moss and berries were a poor substitute._ _

“I want you so bad…” the neko whispered against his neck, tongue and lips leaving a burning trail across his skin.  
“I know, but that might not be such a good idea right now… you are rather _intense _and I need to be able to walk back to camp by the end of the day” the scientist chuckled, hands brushing through Ciel’s half wet navy blue locks. The fresh spring water was crystal clear, allowing Sebastian a clear view of the neko’s want. It glowed a vibrant blue and the movement of the water seemed to throw the light beneath the surface, painting their naked forms in a mosaic of blues.__

____

____“It doesn’t have to go all the way” Ciel pressed his forehead against the scientist’s, duel coloured eyes pleading and heated. Animalistic. Ciel wanted the scientist underneath him again, that much was clear, but Sebastian worried that he’d already been away from camp too long. Surely someone would have noticed by now._ _ _ _

____“Let me make you feel good-” Ciel suddenly broke off, head turning to the far end of the cave, his ears swivelled to catch sounds that were too quiet for Sebastian to hear and they both seemed to hold their breath for a moment. The neko stepped back, brows furrowed as he reluctantly untangled their limbs._ _ _ _

____“Humans… your humans” Ciel ears flattened momentarily, he didn’t want to leave his mate, he loved the crimson eyed human, Sebastian made him feel less lonely, made his heart beat faster. He wanted the human to be safe. But he couldn’t get caught, who knows what would happen if the others encountered him…_ _ _ _

____“I have to leave now”  
“Ciel wait!” Sebastian grabbed onto his arm before the neko could flee and Ciel crashed his lips one last time to his human’s. They broke apart panting, Sebastian’s lip bleeding a little where he’d accidentally run into Ciel’s fang but he couldn’t care less as he took in the sheer adoration on the creature’s face._ _ _ _

____“I love you…” the neko whispered, but in the quiet and echoey cave it might as well have been a shout. It certainly felt like thunder to the scientist as his heart seemed to simultaneously speed up and stop all at once.  
“I love you too” Sebastian smiled softly, hand still tightly holding the neko’s._ _ _ _

____Ciel slipped away and ducked under the water to swim through a hidden exit and before Sebastian knew it search lights were flashing through the cave, bathing the dim space in streaks of blinding light._ _ _ _

____He already missed the neko, he wanted to see those beautiful eyes again and feel his warm hands. He missed how Ciel’s tails would wrap around his legs and the neko would cling onto him like Sebastian was the only thing he ever needed._ _ _ _

____But as a bright light shone into his eyes, he knew he wouldn’t be seeing the mysterious creature anytime soon. First he’d have to find some way of explaining why he was stark naked in a cave in some random spring._ _ _ _

____\--_ _ _ _

____“You lost your clothes?”  
“Uhhhhh…” Sebastian, feeling like a complete twat, unsurely responded with a hesitant “…yes”_ _ _ _

____The man looked at him for a long moment, torch pointed away from Sebastian’s face, but also away from his naked body submerged in the all too clear spring water. He sighed and started taking off his jacket, the caves were far cooler than the rest of the island, so he had on a whim decided to wear one, although he’d never imagined that it would be used quite like this._ _ _ _

____“Here, use my jacket, I’ll radio in to let the camp know that we found you. Jesus Michaelis, you’re in so much trouble, you’ve been missing for over 24 hours, you didn’t take your radio!” the man shook his head and turned around to contact the rest of the search team and give the nude scientist some privacy._ _ _ _

____Sebastian quickly got out of the pool, he wondered where Ciel had disappeared off to and wished he had followed the neko, or at least brought a towel with him. In all their heated exploits the scientist had never given any thought to the fact that he didn’t have any clothing. Sebastian felt his cheeks grow hot, he dreaded leaving the cave and taking the walk of shame practically butt naked all the way back to the camp._ _ _ _

____He slipped the jacket on his still wet body, but it was too short to cover all the starches and hickeys on his thighs, he loved Ciel, but this situation was honestly a nightmare. Sebastian futilely tried to pull the jacket lower to cover his rear, but all it did was expose his ‘colourful’ neck and- shit was that a bite mark on his shoulder? Sebastian frantically tried to think of a better explanation for all this._ _ _ _

______“I got lost”  
“What?” the man asked grumpily as he placed his radio back in its holster, clearly he was still upset with the runaway scientist.  
“I wondered off at night during the party and I got lost in the dark” Sebastian explained lamely.  
“Well that was dumb”  
“I know, I won’t do it again”  
“You’ll be lucky if the higher ups even let you out of the camp again” the man huffed and Sebastian felt dread pool in his stomach… 

____\--_ _ _ _

______“Since you are such a valuable member of the research team and you have had nothing but a pristine record for quality work in the past, I shall not restrict you to the camp grounds” Sebastian sighed a breath of relief at his superior’s words.  
“However, this behaviour is completely unacceptable, what if you had gotten injured or even died? No one knew your whereabouts, no one had radio contact with you. Mr Sebastian Michaelis you no longer have permission to wonder Toboso island alone” Mr Spears’ eyes roamed the tent where those involved were gathered to hear what the project manager and lead scientist had to say about Michaelis’ disappearing act.  
“From now on Mr Faustus will accompany you on all expeditions you take part in”  
“But sir-” Sebastian tried to complain but was cut off.  
“You’re lucky I’m not sending you home. Dismissed” he waved them all off, and the tent’s occupants filtered out. 

____“You better get some food Michaelis, you must be hungry” Claude tapped him on the shoulder to get his attention and Sebastian was pulled out of his thoughts.  
“What? Oh, yeah” the scientist adjusted his collar but still felt too exposed, he took pride in his work, and this situation was a mess. Food was the last thing on his mind, all he could think about was the captivating neko that had stolen his heart and the massive problem that was working out how to take the neko home with him._ _ _ _

____\--_ _ _ _

____Within the zoologist’s tent, Sebastian prepared a kit so that he could obtain a sample of Ciel’s slick. It contained specialised glass slides he could place a sample between for examination under a microscope, several test tubes, a few cotton swabs and ziplock bags to put them in. Sebastian was simply fascinated by the slick’s chemical properties, he wanted to get it analysed as soon as possible. But it would have to wait until he returned to the mainland as they didn’t have machinery sophisticated enough on Toboso island for the kind of tests he wanted to run._ _ _ _

____It had been a few days and Sebastian hadn’t seen hide or hair of Ciel, the neko hadn’t visited his tent and he’d not been able to leave to find the creature himself. Perhaps Ciel still felt guilty for being rough with him, or maybe he was just wary of other humans finding him, either way it was concerning to the scientist._ _ _ _

____The only time he had left the camp was to go down to the shoreline some twenty metres away and even then Claude followed him like a bad smell. The entomologist seemed to have taken Spear’s orders very seriously and there wasn’t a lot Sebastian could do or say to get him to leave him alone. He’d tried._ _ _ _

“So, what are you doing now?” Claude asked, hovering by his side as he prepared his bag to go on another expedition into the rainforest.  
“I can’t just sit in camp all day, I _am _being paid to do research you know” Sebastian responded testily.__

____

______Claude Faustus was kinda creepy, but most of the entomology crowd were so that wasn’t all that surprising. To make things worse Faustus specialized in spiders and the thought alone made Sebastian’s skin crawl, cats were far better than spiders and even though in zoology he studied a wide range of animals, mammals were by far his favourite. Why couldn’t Claude specialise in butterflies or moths? They were at least somewhat cute._ _ _ _ _ _

____

______Sebastian sighed “I’m thinking of heading to the eastern side of the island”  
“You know they found your clothes in a ditch not far from the cave you were in” Claude had a look on his face that Sebastian couldn’t understand. It gave him a bad feeling._ _ _ _ _ _

____

______The zoologist shrugged “that’s pretty weird-”  
“They were torn up” Claude interrupted “like an animal ripped them apart or something…” Sebastian didn’t respond. He merely shrugged and continued packing his bag, but uncertainty and worry bubbled inside of him as the golden eyed man quietly watched him pack._ _ _ _ _ _

____

**Notes for the Chapter:**

> Thank you so much for reading! I hope you enjoyed it, even if it was a little shorter than some of my other chapters. I'd like to give a huge thanks everyone who left comments and kudos on this fic, I wouldn't have been able to create so much stuff without all of your amazing support!


	8. Analysis

**Summary for the Chapter:**

> Distance makes the heart grow fonder, or so they say. Sebastian would much rather spend time with his neko boyfriend than Claude Faustus...

**Notes for the Chapter:**

> I've been writing a lot of Soot and Kisses, sorry for the delay in updating this fic! I hope you guys enjoy the this new chapter!

“You know Claude, you don’t have to follow me on every expedition away from camp” Sebastian complained as he scribbled notes down on a pad of worn paper, documenting his observations about a small unimportant beetle scurrying across the trunk of a tree.

“You disappeared for over 24 hours, people suspected that you had gotten yourself killed on the cliffs or bitten by some poisonous animal” Faustus answered coldly, clearly not willing to go against orders and allow Sebastian the freedom he desired. And while Sebastian had not fallen off any cliffs he was certainly bitten in those wonderful 24 hours, he still had the hickeys on his thighs, not that he’d be telling Claude that anytime soon.

It was actually creepy just how much the entomologist followed him. Sebastian could barely find the time to take a leak alone with the Claude hovering over his every move. The zoologist found himself missing Ciel more and more with every hour they were apart, he missed Ciel’s soft tails and ears, his stunning heterochromatic eyes, and even the rough brush of the neko’s tongue tasting his skin. But perhaps the thing he missed the most, was Ciel’s wonderfully alien dick.

The bioluminescent member was peculiar in every way, completely unlike anything he’d ever seen before. From its textured spiral exterior to the ticklish little tentacles that accompanied the display, it even tasted good and Ciel’s natural slick made his skin tingle in ways he’d never felt. Truly it was a marvel of nature, and Ciel knew how to use it to. Attractive, intelligent, really fucking good in bed, his neko love had it all.

But if Ciel was paradise, Claude was hell.

“Claude, I’m going to head back to camp, why don’t you stay and continue documenting these bugs. I think I saw one with seven legs, you might wanna check that out, it could have the whole entomology community up in arms about whether it’s a spider or an insect” Claude frowned at that, rolling his eyes as the scientist tried once again to escape him.

“I don’t think so, Mr Michaelis. That would go directly against orders form the higher ups, and I for one intend to keep my job” Claude denied him.

As the day progressed Sebastian found himself not enjoying field research for the first time in his career. He usually loved actually observing the species he was researching. But today he just couldn’t get the neko off his mind, it drove him mad. 

Colourful birds flew suddenly from the trees, their screeches loud and startling. Sebastian spun around, looking for the bug scientist in the dense rainforest, but found himself unusually alone.

“Claude?” he called out, but nothing answered him.

“That’s not the name I want you to be yelling” a beautiful voice whispered in his ear and he felt the cat’s sharp teeth scrape lightly across the skin of his neck.

“Ciel? What happened to Claude?” Sebastian asked, leaning back into the neko’s firm embrace.

“I pushed him into some bushes, come on we have to hurry” Ciel told him before quickly scooping up the human and throwing him over his shoulder. Sebastian yelped in surprise as he was awkwardly carried off and they quickly left that patch of jungle behind. Well this was one way to escape Faustus Sebastian thought with an internal chuckle. At least he was able to watch Ciel’s back side as he ran so it wasn’t all bad.

They settled in a dense grove of trees after a few minutes of running and Sebastian was carefully placed on the ground. The neko was immediately on top of him, clawed hands sneaking under his shirt and running across his skin. The cat’s mouth crashed into his, teeth nipping his lips as the half cat’s rough slightly bristly tongue entwined with his own.

“Ciel, I missed you so much” Sebastian gasped between kisses, already breathless as the neko’s hand dipped down his trousers and rubbed his quickly hardening want.

“I missed you too” Ciel spoke between rough kisses, he felt his mate's tongue catch on a fang, coppery blood only fuelling the neko's desire.

“I missed my beautiful mate” he added when they finally parted. Ciel stared into Sebastian’s deep red eyes and felt fire crackle and burn between his own legs. The neko's own eyes were wild with need, his overwhelming desire and lust turned his pupils into thin predatory lines. And Sebastian was the prey beneath the predator. 

“Don’t leave me alone again, I want you so bad” Ciel begged as his glowing member quickly protruded from his slit, dripping and hard. Even the little tentacles wiggled as they extended, fanning out like an exotic flower to lure the scientist in. 

Ciel moaned as Sebastian wrapped his hand around the neko’s length, thumb rubbing the tip. The scientist’s hand tingled due to the copious amounts of slick dripping from the glowing cock as the half cat rocked into his hand desperately.

“Let me top this time” Sebastian asked, smirk stretching across his lips as he watched the neko writhe and whine. Ciel nodded, hands pulling at the scientist’s clothes as he buried his head in Sebastian’s shoulder. His cheeks were surprisingly red since he’d never actually been taken that way before. In the few times he had mated with others he’d always been the one on top, he’d never done it any other way, and he’d never had the chance since his race had given up their sentience.

“I haven't done it that way before” he admitted. 

“That's alright, let me make you feel good” Sebastian stroked the neko, pulling whines and moans from the cat’s rosy lips. He gathered up some slick, making sure it coated his hand thoroughly and just rubbed at Ciel’s entrance, wanting his love to relax and enjoy the experience.

“Can you turn around?” The scientist asked, it would be easier for Ciel’s first time that way.

“I trust you” the neko kissed his cheek softly before he turned, hands grabbing a hold of a nearby tree trunk to ground himself. Sebastian pushed in a single finger, watching the neko's every move for signs of discomfort as he softly prepped Ciel. 

“Don't hold back, I want you to take me properly” the neko demanded, apparently not liking the gentle treatment. The scientist responded by adding a second finger making Ciel squirm as they probed inside him, scissoring and stretching his entrance. Sebastian pulled out his fingers only to wrap them around the cat's glowing member to collect more lube, the firm strokes had Ciel moaning and he was somewhat disappointed when his human released him again. _Such a tease _. But Sebastian made up for it though by pushing three fingers inside him and digging around for his prostate, grinning when the half cat moaned and shivered in response, tails curling in pleasure.__

__“All I could think about was being with you again, Ciel I've missed you so much” Sebastian told him as he wrapped an arm around his waist and thrust his fingers in deeper still._ _

__“Sebastian…” the neko whined, cock achingly hard as his tentacles spasmed with need. He desperately wanted to whirl around, bend the scientist over, and have his way with him, but he had already agreed to let the scientist fuck him, he just had to be patient._ _

__“Take me already” Ciel whined as he felt slick drip down his legs the more he was made to wait. The neko was answered with the sound of a zipper being pulled down. The fingers left his entrance and were replaced with the head of Sebastian's cock pressing against his hole._ _

__“Are you sure?”_ _

__“Please!” Ciel whined, pushing back eagerly. Sebastian slowly sunk in, moaning as the tight heat enveloped his length. The neko had never felt this before, it was strange in the best of ways. His love filled him, pushing in inch by inch until he could go no deeper and Ciel gripped the tree tighter, scratching deep claw marks into the bark as his partner bottomed out. Sebastian stayed still inside the neko despite his body screaming at him to move, he rubbed the neko's hips, watching as the cat's tails fluttered and twitched and tickled his chest._ _

__“Why are you so gentle with me” Ciel asked as he felt the scientist litter the back of his neck with soft kisses._ _

__“Because I love you” Sebastian chuckled, confused as to why Ciel was objecting._ _

__“Then show me!” The cat demanded. He squeezed his walls around the thick cock buried inside him, trying to get the scientist to move already, the move rewarded the neko with a low moan, hands gripping his hips harder in response._ _

__“As you wish kitten” Sebastian smirked and pulled out until just the tip was inside so he could thrust it all back in harshly. He roughly pulled back the neko's tails, giving himself more room as he started up a long and hard pace, his large cock being eagerly swallowed with each thrust. Ciel moaned and whined, pleasure running through him as the scientist pounded his rear. And although it was a weird new feeling, it felt so right. He loved the slight pain of being stretched, especially when Sebastian pulled on his tails, and the human had even used his natural slick to coat his member, Ciel had never felt its effects in such a sensitive place before, it set his insides on fire. A hand wrapped around his glowing need and stroked him in time with each snap of the man's hips, only making the neko drown in more pleasure. Ciel pulled his ears back, sharp teeth itching to bite down on his mate's skin, but he'd have to wait until next time._ _

__Ciel came surprisingly quickly, seed spraying over the tree he was leaning on. His cock throbbed and pulsed with each spurt, neon blue flashing brightly, but the neko was far from finished._ _

__“Keep going!” He demanded as Sebastian's hips slowed. Ciel was still hard and he bent himself further down to allow his love to reach deeper and fuck him harder. It made Sebastian gasp and moan at the new angle, his hips snapping bruisingly hard against Ciel's plush rear. Sebastian dug his fingers into the neko’s slit and stroked him faster, the tentacles tickled his hand as he pleasured Ciel from both ends. The scientist found himself tipping towards completion, and the stray thought of Claude finding them crossed his mind, but it was immediately overridden though by the tightness and tingling heat around his cock, the neko's unusual slick making him ten times more sensitive._ _

__Sebastian came with jerking hips as he filled the half cat, he moaned as the neko tightened around his length and milked his cock. Ciel came again as well, the feeling of cum painting his insides sending him over the edge once more. His glowing cock flashed vibrantly he released for the second time and they both panted together, sweaty and wet, but content._ _

__Sebastian carefully slipped out, arms immediately holding Ciel close to him. He showered the cat in kisses and the neko lazily returned them. The front of his pants had been thoroughly dampened by the neko's slick and their passionate romp, but the scientist couldn't bring himself to care at the moment. He was happy enough just having Ciel with him once again, and together they sunk to the jungle floor. They were both unusually clingy and neither wanted to part. The neko purred in his lap, blue ears brushing his cheek as Ciel nuzzled under his chin, kittenish licks brushing against his neck._ _

__The scientist stroked Ciel's head, fingers running through his soft slate coloured hair. He didn't want to leave. Didn't want to go back to camp to his lonely sleeping bag. A ship would arrive in only a few weeks and the research team would leave Toboso Island. The scientist’s worry increased, he couldn't imagine leaving Ciel behind._ _

__\--_ _

Sebastian held the test tube up in the lamp light of his tent. He tilted the tube side to side, watching the semitransparent viscous liquid slide back and forth slowly. He pushed up his glasses that had slipped slightly down his nose and recorded his observations on a private document on his computer. The zoologist poured out a sample of the slick on a small glass square before sealing it with another piece, he wasn't a chemist, but the slick was worth looking at under a microscope. He knew that the liquid made everything more sensitive, made his skin tingle even if it was applied on areas that weren’t sexually sensitive, but he had no clue as to _how _the substance did what it did. Sebastian had never seen anything like it before.__

____

____He pushed the slide under his small travel microscope and adjusted the lens, leaning in to examine the specimen. But he was interrupted by Claude, the other scientist barged into his tent, well as much as one could barge into a tent, he roughly pulled down the zipper and stepped inside, scowl on his face._ _ _ _

____

____“Something knocked me over and by the time I got up you were gone!” Faustus complained, still pulling leaves and debris off his clothes and hair._ _ _ _

____

____“Was it a bird?” Sebastian asked, he'd already closed the document as soon as he heard the zip to the tent opening._ _ _ _

____

____“No! Michaelis, did you push me?” Claude asked, unusually peeved. The man was usually pretty stoic and such emotion from him was uncommon._ _ _ _

____

____“I wouldn't stoop so low as to chuck you in some bushes and run, I'm sure it was just an accident” Sebastian struggled to keep a straight face._ _ _ _

____

____“And so you left me behind?”_ _ _ _

____

____“I didn't notice you were gone” the scientist lied but maintained an innocent facade. He focused on trying to analyse the slick and pointedly avoided looking up at Claude._ _ _ _

____

____His colleague sighed, not believing the other. Michaelis was up to no good. He suspected the man had been explicitly mingling with a humanoid animal, had practically seen pictures of it on his laptop. He just needed evidence to expose the man and the new species he had been hiding from everybody..._ _ _ _

____

**Notes for the Chapter:**

> Comments and kudos are much loved and appreciated! I'm unsure if the smut in this chapter is any good though? Feedback on that would be very helpful!


	9. Ignition

**Summary for the Chapter:**

> Ciel's back and feeling possessive, he wants Sebastian all to himself, but the humans keep getting in the way... so he decides to take the initiative

**Notes for the Chapter:**

> Sorry for the long wait, enjoy this new chapter!

“What do you want Alois?” Ciel grumbled, rolling over to lie on his stomach, twin tails flickering in agitation as he relaxed on a large flat rock. 

“What, I can’t admire a lovely view?” The blond neko huffed, leaving his ‘hiding’ place behind a large tree. The blue haired neko stretched, looking more like a starfish than a cat as he lounged on the warm sun heated boulder, he closed his duel coloured eyes, ears swivelling from his annoying friend to the enticing sound of birds singing in the branches. The lanky body of Alois was quickly draped across his own, a bristled tongue lapping behind his ear as the sandy coloured neko purred.

“It’s mating season”

“So”

The blond rolled his hips against Ciel’s ass, hands trailing down the blue half cat’s torso. Ciel hissed, a rough warning tone that had the other neko rolling off to lounge beside him on the rock.

“You’re always so picky!” Alois complained, pout on his lips as his icy blue eyes watered comically. Ciel gave him a quick bark of laughter and a light shove before conflictingly pulling him closer to rest his head on the blond’s chest, drawn to the other boy’s heat.

“We’re still too young to mate” Ciel mumbled, the warm sun making him drowsy. They almost entirely matured, but youth showed in their thin limbs and wide eyes, showed in their smaller size, their tails still too long for their bodies.

“I don’t know about you, but I got my lures this year, I’m practically an old man!” Alois exclaimed, his overly dramatic nature pulling a smile from the other neko’s lips. Despite Ciel’s earlier objection the two teens gradually inched closer together, limbs and tails tangling as the sun warmed them up.

“More of us are turning into small beasts, they say the fish in the sea are filled with poison?” Ciel frowned, heart hurting at the memory of finding one of his kind dead on the cliff rocks, foam around his mouth and flesh grey and sunken as birds picked at his body. He’d never forget the smell. Death and rot was such a visceral smell, he could still remember the gag that had pulled on his guts and threatened to upend his breakfast.

“I’m never going to turn, they’re not the same afterwards… it’s like their minds become small along with their bodies” Ciel explained, fear and defiance in his eyes as he looked up at Alois.

“I came here to spend my heat with you and you’re all doom and gloom. Just stick to prey on the island and you’ll be fine” the blond neko shrugged, brushing off Ciel’s concern, his fluffy tails tickling the other boy’s legs as they flickered in agitation.

“How do you know your heat has started?” Ciel tilted his head.

“I just know, I feel it in my gut” the blond tried to explain, hands wandering across Ciel’s bare flesh, every inch they drifted over tingling with heat.

“I can never tell” the blue furred neko huffed, always annoyed when his body sprung a heat on him without warning. His family line was renowned for their impressive bodies, their vibrant blue displays the envy of most nekos. But impressive displays weren’t all good, when his heat neared Ciel often found himself feeling unreasonably angry all the time, he was quick to argue, had become aggressively territorial and desperately horny (although he refused to bow to instinct and had so far spent every heat in a quiet cave with just his hand and a lot of growling).

Ciel’s heats had only been growing in temperament, each new heat shaking him up more than the last. He’d had lures already for three winters now, each winter adding another thin blue tentacle to his display. Nekos didn’t stick together and once a litter was able to hunt and survive they were kicked out of the nest and left to find their own territory, although they weren’t too aggressive to visiting family. They stayed alone unless they were mates, but there were exceptions. Alois had been his childhood friend for years, they’d grown up together, played as kits together, Ciel even let him hunt in his territory occasionally. He probably should have chased Alois away by now, he could already smell the sickly sweet scent of heat on the other neko’s body and didn’t want to take advantage of him. There was also a good chance that Alois’ heat would trigger his own. He should have hissed and swore and chased the cute blond into the next patch of forest. 

But he didn't.

Ciel only pulled him closer and rubbed the underside of his chin across the other’s skin, covered the boy in his scent as he kissed claiming bruises across his neck and chest. Their limbs tangled, hips grinding against each other as they clawed for purchase. 

Ciel’s hand slipped between them to stroke their glowing lengths together, Alois mewled, voice whiny and high as he pulled the other neko tighter against him. His purple and gold length didn’t shine as brightly as Ciel’s, wasn't as impressive, but the blond couldn’t care about insecurities when the other was touching him like that. He was smooth and lacked texture, where Ciel was ribbed with a raised line that spiralled around his length, three flat leaf shaped lures, similar to the petals of a flower surrounded him contrasting Ciel’s thinner cluster of lures. The blue glowing neko looked amazing pressed so close to him, it might have been the heat clouding his mind, but the little blond couldn’t get enough of him.

Sticky and hot and suffocating. That’s how it felt for Alois when the other neko laid atop him, but he loved every second of it. The blue haired neko bit into his shoulder and Alois gasped, Ciel growled, his fangs drawing blood as they desperately fumbled together. Every inch of Ciel reeked of a near suffocating heavy sweetness, the slick from his arousal near burning against the blond’s skin.

It seemed that he wasn’t the only one in heat...

\--

Ciel smiled as he lounged on a large warm rock, it was fairly flat and high up, let him spy on the humans comfortably without being seen. He soaked up the last of the afternoon sun, splayed like a starfish as he felt the warm rays heat up his blue fur. It had been such a long time since he’d thought of Alois, longer still that he’d remembered their first heat together, the blond neko had been the closest thing to a friend he’d ever had, closest thing he’d ever had to a mate before the crimson eyed human.

When Alois had given up his form to join the rest of his kind as jungle cats he’d been disheartened, he had almost given up as well until Sebastian came to the island. Who could have guessed that his mate wouldn’t even be one of his own species, and while other nekos would have found the scientist’s plain loins unattractive, Ciel was enchanted by his entirety, from the way he smelt to the sound of his voice. Sebastian was healthy and handsome, kind and funny, and he always paid attention to the neko, even when he had human work to complete, he never wanted to leave the man’s side.

The neko looked down at the camp sneakily, ears perked and attentive as he searched for his love’s den amongst the tents. He’d give the human some much needed company in the scientist’s personal den since Sebastian wasn’t allowed to travel the island alone anymore, without that annoying human following his mate. As soon as the sun dipped below the waves and darkness fell on the island the neko stalked the sandy shore, taking care not to be spotted by any of the pesky humans as he slipped into Sebastian’s tent.

\--

Ciel breathed in deeply, the scent of his mate hung deliciously in the air, it made him feel a burst of happiness in his chest as his bright dual coloured eyes searched the dimly lit contents of the small den. There was a little desk and a laptop, some weird human science equipment and Sebastian’s bags containing his clothes and other belongings, but Ciel ignored all those useless items, gaze falling instead to the lump of his mate’s sleeping bag. 

Since he couldn’t take Sebastian away, he’d just have to stay here with his human. The den was small unlike the large winding caverns of the island, but he didn’t mind so long as he had his mate with him. 

Carefully Ciel peeled back a corner of the large sleeping bag, trying not to wake up his love, it would be a squeeze for both of them to fit, but that just meant that he’d be especially close to the scientist. The half cat shimmied in, arms wrapping around Sebastian’s chest and drifting lower as he pressed his lips to the back of his mate’s neck, rough tongue flicking out to give the patch of skin a taste. 

The man drowsily started to wake up and that’s when Ciel realised that this human smelt nothing like his mate, his scent was mingled with Sebastian’s since he was sleeping in the man’s bed, but his body was too small, hair cut a different way and he tasted awful in comparison to the intoxicating flavour of his mate. 

“Wah?” The stranger mumbled and Ciel hissed harshly, claws extending to dig into the man’s bed shirt. 

“W-what? What’s goin’ on, who are you?” the imposter asked, head trying to turn around as Ciel growled lowly, the sound vibrating at the back of his throat. The neko was seconds away from attacking this human if he made the wrong move.

“Where is Sebastian!” Ciel demanded, confusion, fear and jealousy clouding his mind. _Did this human belong to Sebastian, were they mating? _Just the thought of Sebastian loving anyone else had his heart breaking in two. His eyes watered as he imagined his mate and this pathetic human being together intimately, surly Sebastian preferred him? Didn’t he…__

__The neko’s eyes shone brightly in the dark, their faint glow lighting up the stranger’s face as he turned around. This human was blond, his eyes a rich fern green although they were tinged with red where he might have been crying earlier, he seemed confused and sleepy, not quite able to understand what was happening yet._ _

__The tent flap opened, Sebastian walked in with two hot chocolates, he seemed to freeze as soon as he heard Ciel’s growling. The scientist put the drinks down on the table and switched on his desk lamp, his fears were confirmed as soon as he saw Ciel’s blue furred ears pulled back in a snarl. The neko quickly wiggled out of the sleeping bag, Finny’s cheeks blushing a heated red as he realised that the neko was entirely naked._ _

The half cat grabbed onto Sebastian’s arm, gaze still locked on the strange new human, Ciel felt the overwhelming urge to claim his mate, to ensure that this other human knew that Sebastian was _his _. Ciel slammed his mouth against Sebastian’s, hand tugging the startled scientist’s hair as he eyed the stranger in contempt. He sucked on the man’s bottom lip before pulling back, eyes flickering back to his dazed mate, his immense possessiveness tempered somewhat by Sebastian’s closeness and the familiar taste of him on his lips.__

____

____“Finny, this is Ciel” he gestured to the smug cat humanoid still hanging off his arm, the scientist’s eyes were wide in surprise, a heavy blush staining his cheeks. There was now no avoiding the fact that Ciel and him were intimate, the neko had thoroughly made his claim._ _ _ _

____

“Ciel, this is Finny, he studies plants rather than animals. He was feeling homesick, so I let him crash in my tent” the zoologist explained. Finny had sat up by now, he’d felt awkward seeing his co-worker kiss this strange new person, like he shouldn’t have been there. The dim lamp light allowing him to see all of Ciel’s peculiar features, his twin tails, large catlike ears and his heterochromatic purple and blue eyes that were still glowing threateningly. The cat hissed again, showing off his large fangs and sharp teeth as he pressed himself closer to the crimson eyed scientist, _was Ciel threatened by me? _Finny wondered.__

______ _ _

______“It’s okay Ciel” Sebastian stroked the half cat’s head, hand giving one of his fuzzy ears a soothing rub. The neko’s eyes slowly dropped, lids falling until there was only a sliver of his eyes shown between long lashes, he purred loudly, the sound rumbling in his chest as he pressed his face against the man’s shoulder, enjoying the scientist's calming touch. Finny watched as the zoologist instantly diffused the creature’s anger simply by stroking it and rubbing its ear._ _ _ _ _ _

______ _ _

______“Ciel is a neko, I’m pretty sure he’s the last of his kind. But you can’t tell anyone about him, if someone found out they might try to take him away for experimentation, he’d probably end up in captivity for life if they didn't immediately dissect him…” Sebastian explained, his cheeks still tinged with pink._ _ _ _ _ _

______ _ _

______“I can’t believe something like this exists, it’s amazing!” Finny untangled his legs from the sleeping bag and stood up to further inspect the neko. Ciel was surprisingly hairless aside from his more cat like features such as his tails and ears, Finny out of respect didn’t want to look at the neko’s crotch, but at the same time he’d already got a glimpse of Ciel’s unusual genitals and was curious from a purely scientific standpoint._ _ _ _ _ _

______ _ _

______“Ciel, why did you come here?” Sebastian asked, taking a sip of his hot chocolate after passing the botanist his. The neko in question leaned over to sniff at the warm beverage, nose twitching as the scientist extended the cup so Ciel could investigate it properly._ _ _ _ _ _

______ _ _

______“I missed you, I couldn’t smell the Finn human in here, it just smelt like you” Ciel explained (although Sebastian knew he'd gotten Finny's name wrong on purpose). Ciel's tongue darted out to experimentally taste the hot chocolate, he quickly decided that he liked the sweet beverage and stole it from the scientist’s grasp, hands pulling it towards him so that he could lick off all the chocolate powder sprinkled on top. Sebastian merely smiled fondly, his exacerbation numbed at the sight of Ciel with milky hot chocolate on the tip of his nose._ _ _ _ _ _

______ _ _

“It’s dangerous to come into camp, what if someone had seen you” the zoologist sighed, Ciel simply scoffed, waving it off with a flick of his tails. Finny was a harmless botanist, he probably wouldn’t tell anyone, but having _anyone _find out about Ciel put him on edge, there was too much risk, too much uncertainty.__

________ _ _ _ _

________“It’s like a slumber party!” Finny cheered, childishly excited at the prospect of hanging out with Sebastian and Ciel. The zoologist sighed as Finny explained to a confused Ciel what sleep overs were, perhaps for tonight it would be okay if Ciel stayed here, if Finny became friends with the neko then he wouldn’t have to worry about the blond ratting him out..._ _ _ _ _ _ _ _

________ _ _ _ _

________\--_ _ _ _ _ _ _ _

________ _ _ _ _

________It had to be close to 3am now, the tent was finally settling down and Sebastian was exhausted. Thankfully Ciel didn’t feel the need to assert his claim over Sebastian again, sitting in the man’s lap made Ciel feel secure enough to tolerate Finny’s presence. The zoologist had pulled out a spare sleeping bag for him and Ciel to crash in but the neko had instead spent his time raiding Sebastian's suitcase and making a fort out of the man's clothes, he had then surrounded their bed with it, meticulously placing each piece of clothing in a delicate circle. Finny found it cute, Sebastian was mildly annoyed that he'd have to pack his clothes again when the neko left, but Ciel was purring so happily that he couldn't complain._ _ _ _ _ _ _ _

________ _ _ _ _

________The blond botanist had fallen asleep eventually, leaving them somewhat alone together. Luckily Ciel managed to keep his hands to himself while Finny was awake, but as soon as the other human was sleeping the neko was on him, mouth sucking bruises across his chest as his hands wandered under his clothes._ _ _ _ _ _ _ _

________ _ _ _ _

________“Ciel” Sebastian whispered reluctantly, “we can't do this now, not when Finny's here” Ciel huffed, a low growl rumbling in the back of his throat, but he behaved, for now. The neko was almost too hot above him, his body wrapped around the scientist’s, arousal ruining the front of Sebastian's bed shirt. He smelt strongly musky, which was odd to the scientist as he'd never noticed such a smell before. But as the neko’s glowing eyes closed, Sebastian was able to relax as well, he'd smuggle Ciel out of the camp in the morning, appeal his punishment and ditch his mandatory stalker Claude by offering to work overtime and do extra paperwork (which his boss William would certainly appreciate), he might even be able to get Finny to help cover for him so that he could see Ciel more._ _ _ _ _ _ _ _

________ _ _ _ _

In fact, now that he had Finny to help, the _‘escape Toboso island with his hot neko boyfriend’ _plan, was far more likely to actually work.__

__________ _ _ _ _ _ _

__________Or so he thought._ _ _ _ _ _ _ _ _ _

__________ _ _ _ _ _ _

__________The sun rose, and with it a shitstorm of new problems, namely, one horny neko who'd just gone into heat._ _ _ _ _ _ _ _ _ _

__________ _ _ _ _ _ _

__________It was matting season…_ _ _ _ _ _ _ _ _ _

__________ _ _ _ _ _ _

**Notes for the Chapter:**

> Comments and kudos really help motivate me! tell me what you think of this chapter?


	10. Boiling Point

**Notes for the Chapter:**

> Thank you Demonofphantomhive for beta reading this for me!  
> Hope you guys like this chapter!

The air reeked of it. Thick and clammy, the musky smell of the neko's heat permeated the tent’s small space with a hot sweetness that smelt rougher to the human nose, bitter and tangy. The half cat moaned, low and ragged, his face buried in the back of the scientist's neck as he rutted against the man's backside. The heat sent Ciel's body into overdrive and his glowing arousal drenched Sebastian's pyjamas in a wet and tingly natural lube. 

“Ciel! What are you doing? Finny is still here” Sebastian whisper yelled, but the neko’s heavy desire started to encourage his own body’s ill timed reaction. Ciel hissed in his ear, pupils blown wide as his tentacle like lures tickled the man’s skin, the neko was lost to logic and reason, all he knew was that he wanted Sebastian.

He wanted his mate _now _.__

__His hands slipped under the man’s shirt, sharps claws trailing across Sebastian’s skin as the half cat moaned behind him, the sound frighteningly animalistic. Finny sat up from across the tent, his eyebrows furrowed as he tried to work out what that smell was and why it was so hot in here. Sebastian tried to untangle himself from the neko, those desperate hands clinging stubbornly as Ciel whined, ears pulling back as another wave of heat flooded the neko’s body and all his nerves screamed at him not to let his mate go._ _

__Ciel meowed. It was tiny, his voice small and desperate as he panted, fingers stubbornly holding on to the edge of Sebastian’s shirt as he left the nest of clothes and the sleeping bag. He sounded like a kitten, his dual coloured eyes glowing shockingly brightly, even in the daylight._ _

__Something was wrong with Ciel. Something the scientist didn’t know about, he put a hand to the neko’s forehead and found his skin was hot and sweaty. But Ciel kept trying to press into it, tried to rub his cheek on the zoologist’s palm all needy and hot._ _

__“I think Ciel’s sick!” Sebastian answered Finny’s unspoken question, they looked at each other in bewilderment and a slight amount of panic before turning back to the neko. Ciel’s skin was flushed a ripe pink, his body covered in a fine sheen of sweat, his tails flickered and wagged, unable to keep still while his hips shuffled, desperate for the slightest amount of friction._ _

__“Should we get Madam Red in?” the blond botanist asked but Sebastian shook his head, he didn’t want anyone else to know about Ciel, and that included the camp’s nosy physician._ _

__“He can’t stay in the camp” Sebastian stressed, “if Claude finds him we’re doomed, that man will rat us out to Will and then who knows what will happen to Ciel!”_ _

__“You should go tell Claude that you’re doing paperwork today and that he should leave you alone for today” Finny suggested. It was a decent plan, simple and effective, once they had Claude off their backs they could devote the whole day to looking after Ciel._ _

__“Keep an eye on him, try and keep him quiet-”_ _

__“Woah!” Finny interrupted, he’d stepped closer to Ciel and had gotten a proper look at the neko’s vibrantly glowing cock, his previous curiosity unfortunately sated. The neon blue pulsed with the half cat’s fast heartbeat and his tentacle like attachments wriggled and writhed, spread out like the petals of a flower as the neko lay on his back, hand rubbing against his abdomen in an attempt at easing the pain._ _

__Ciel panted, ears pulled back in distress and eyes lidded as his member throbbed almost unbearably, its bright electric blue mesmerising. Even the inside of his mouth glowed blue along with his eyes and genitals as he pushed his face into the side of the nest, the smell of Sebastian’s clothes was a small comfort._ _

__“Is that normal?!” The young blond scientist questioned, slightly distressed as Ciel moaned louder, the half cat’s breath was rough and laboured and he looked like he was in pain._ _

__It took Sebastian an embarrassingly long to put the pieces together, he was supposed to be a zoologist for god’s sake, it was his job to know about the behaviour of animals. Ciel was obviously going through a rut, (or some kind of heat?) he was unsure of the specifics, but either way Ciel’s raging hard on should have been a dead giveaway._ _

__“Fuck. He’s in heat” Sebastian’s conclusion only further freaked out Finny._ _

__“But isn’t he the last of his kind? What are we supposed to do!” The botanist ran his hands through his hair, trying to stay calm and failing._ _

__“Get a hold of yourself! Ciel’s my partner, I’ll… take care of him, but you need to stay here while I get rid of Claude” Sebastian grabbed the blond’s shoulders and gave him a little shake, crimson eyes serious despite the flush on his cheeks._ _

__“You have to take care of him for ten minutes” the zoologist explained as he grabbed a new shirt, the old one sticky from Ciel's earlier efforts._ _

__“Wah- but, but-” Finny stuttered, face flushed an embarrassed red._ _

__“Just, you know…” Sebastian awkwardly implied with a jerking hand gesture, he didn’t like the idea anymore than Finny did, but they didn’t have any choice._ _

__“I’ll be back as soon as I can” the scientist promised as he ducked out of the tent. Finny gulped, eyes flickering back to the horny neko and his glowing dick that looked like something out of a bad scifi porno._ _

__“You’re doing this to help, you’re doing this to help, you’re doing this to- oh fuck! Its tingly, why is it tingly!” Finny freaked out, his hand hesitantly wrapped around the neko’s bioluminescent prick. It was hot and wet, the glowing member ribbed with a corkscrew spiral and it seemed to grow thicker in the botanist’s hand. Ciel breathed out in relief, the slight touch a balm on his painful erection, the overpowering scent of his own heat covered up Finny’s smell, bitter sweet scent swirling around his head, his senses were swimming in pheromones and he found he could barely tell up from down as the chemicals in his body screamed at him to fuck._ _

__Finny gave the stiff neko a tug, a long whine falling from Ciel’s lips as he bucked into the botanist’s hesitant grip. Already the overpowering slick was making Finny’s hand burn, the neko’s potent chemicals setting off all the nerves across his skin. Finny tried not to look as he ‘helped’ the neko, Ciel’s very vocal moaning not making his task any easier. A heady hiss trailed off into a whiny mewl, loud and deep, and Finny had to cover the neko’s glowing mouth lest he alert the entire camp to his presence._ _

__To his complete mortification the creature licked his hand, bristled tongue sensually tasting the skin of his palm, eyes lidded with a want not meant for the botanist. Finny ripped his hand away and Ciel frowned, confused as his tongue conflicted with his mind. That hand didn't taste like Sebastian, even in his heat addled mind he wasn't a complete fool._ _

__Ciel hissed, batted Finny's hand away and quickly backed up. His whole body was on fire, need and desire burning hotter than it ever had before, but this wasn't Sebastian. This wasn't his mate._ _

__“Seb…” he moaned out between rough pants, eyes bright but unfocused. For a moment he recognised the young blond's face before a rush of powerful chemicals overrode his mind, hand rushing between his legs to grip the base of his cock tightly in pain._ _

__Finny was already praying for the scientist to come back, the neko was hostile to his every movement and it was infinitely clear that the botanist wasn't wanted here. Those teeth and claws looked too threatening to contend with, the inhuman glow of the neko's mouth and eyes repelling Finny even more. He just wanted to study plants! He didn't sign up for this!_ _

__\--_ _

__“What do you mean he ran away?”_ _

__“He ran out of the tent, he was too fast to follow!”_ _

__“... Fuck”_ _

__\--_ _

__Ciel slinked silently through the camp. His every sense was heightened and the light from the sun hurt his eyes, he could hear the rustling of humans doing their strange human work in their little dens and smelt the salt from the sea mingled with foreign humans he’d not smelt before. The neko bit back a pained whine, hand idly stroking his aching length in an attempt to sooth his sexual frustration._ _

__This heat was worse than before, worse than the others, his body seemed to know that he had a mate now and he couldn't be soothed by his usual methods. He needed Sebastian._ _

__Ciel curled up between two tents and hugged his knees, toes digging into the hard-packed sand absentmindedly. Little grains of sand got irritatingly stuck to his blue foot pads and caught on the fur of his tails, but he couldn’t bring himself to care, everything ached too much. The neko closed his eyes and breathed in deeply, trying to pick up the faintest smell of his mate, of Sebastian. He opened his mouth to heighten his sense of smell, revealing the bright blue glow of his tongue, gums and inside of his cheeks. Domestic cats had a special sensory organ (called the vomeronasal organ) in the roof of their mouths that gave them a better sense of smell, nekos unsurprisingly shared this trait._ _

__His eyes shot open, ears swivelling in the direction of his objective._ _

__Sebastian._ _

__He could only just smell him in this confusing jumble of human scents. That, and his own overwhelming scent was throwing him off, its sticky sweetness was thick around him, it clung to his fur and hung around the air. Ciel quietly moved between tents, using his delicate hearing to anticipate the humans’ movements. He finally arrived at a new den, this one had a strange orange skin, but he could smell his Seb here. At first, he struggled with the zip, his hands shaking with nerves and pent up energy as he stood out in the open trying to get to his mate, but eventually he managed to pull the tiny piece of metal down and open the odd den._ _

He flung open the fabric doors only to find a startled human that was distinctly _not _Sebastian. Ciel hissed, displaying his impressive fangs and further startling the confused red head. His tails puffed up in an attempt to make him look bigger and the woman slowly raised her hands in a non threatening manner.__

____

____“What are you?” MeyRin asked to herself as she slowly approached the creature. It entered to tent, stalking closer to her with an unjustified anger. She cautiously outstretched her hand and when she rested it on the creature's head all that anger and aggression seemed to deflate, the neko sagged, his boundless energy suddenly draining. He whimpered glowing dual coloured eyes somehow looking big and sad despite their predatory edge, perhaps it was the low lighting that made his pupils expand like a kitten. The neko sniffed, ears flat against his slate coloured hair._ _ _ _

____

____“Se-Sebastian…” he whined, tears gathering in his eyes. His heat was churning his emotions, playing with them like a mouse beneath a cat's paw. He struggled to keep himself together, all his previous aggression in the face of this strange melting into an all encompassing sadness. He'd smelt the man here, could still smell him, but the lack of his cute crimson eyed scientist severely exacerbated his distress._ _ _ _

____

____“Sebastian?” MeyRin asked, surprised that the new creature could speak English, in fact, everything about this creature was surprising._ _ _ _

____

____The neko nodded, tears were already running down his cheeks. Ciel took in another deep shaky breath, pinpointing the smell of his mate still in the room. The beautifully alluring smell was coming from a stack of folders in a box, probably documents that the scientist had worked on._ _ _ _

____

____“Smells like Seb” the neko pointed to the box and MeyRin, still slowly getting over her initial surprise, managed to piece together the creature's intent._ _ _ _

____

____She pushed up her large round glasses and switched to a purely professional scientific mindset, quickly she examined the creature, identifying its key features. The first was its glowing mouth and genitalia, the second was its feline features, its distinct cat ears and twin tails, the last, its humanoid shape and blatant nudity. It seemed to be in pain but there were no obvious wounds and the sheen of sweat on its skin was unexplainable with the information available._ _ _ _

____

____“He's not here, would you like me to go get him?” She asked, clearly this humanoid creature knew Sebastian, maybe the other scientist could explain what on earth was going on._ _ _ _

____

“Please” Ciel begged, trying to wipe away his stubborn tears. He gingerly sat down on the floor of the tent and curled into a ball, the half cat muffled a groan of pain with his arms as he wrapped his tails around himself. His intense heat crippled him and left him uncomfortably vulnerable with this stranger, he wished he'd just stayed in the nice nest he'd built. He remembered Alois again, remembered the mating season they'd spent together, his heat had not hurt so much then, even alone in the caves he'd not suffered as he did now. He wanted to throw up, felt like passing out, but his member still throbbed, still persisted and he felt the numerous soft little tentacle wiggle and brush against his tummy in agitation, slick dripped from between his legs. He couldn’t stop crying and whatever brief clarity he had gained before was now drowned out by a fresh sea of emotions, pheromones and sickly unbearable _heat _.__

______ _ _

______\--_ _ _ _ _ _

______ _ _

______“Sebastian!”_ _ _ _ _ _

______ _ _

______“Meyrin?”_ _ _ _ _ _

______ _ _

______“I found a weird glowing cat thing!”_ _ _ _ _ _

______ _ _

______“You found Ciel!”_ _ _ _ _ _

______ _ _

______“It ran away though…”_ _ _ _ _ _

______ _ _

______“...Fuck!”_ _ _ _ _ _

______ _ _


	11. Thermogenesis

**Summary for the Chapter:**

> Ciel needs his mate. Now, more than ever. 
> 
> He needs Sebastian...

**Notes for the Chapter:**

> Thanks @llaresll (on tumblr) for coming up with the chapter title! I'd run out of sciencey sounding names and this one's purrfect!

Claude pushed past his fellow scientists, determined to barge into the head scientist William T. Spears' office and tent, and demand a full investigation be initiated against Sebastian Michaels. The man was clearly breaching protocol and if he really was fucking that cat thing, he was probably breaking the law as well! There was evidence on the man's computer, picture proof of his flippant disregard for the scientific method and refusal to properly document new species. 

Spears would take his side for sure, the man was hellbent on following regulations and he wouldn't tolerate a defected scientist, regardless of how good he was at his job.

Claude was entirely certain in his decision to tattle on Michaelis until a very naked, very glowy feline like creature, ran straight into him. The half cat nearly knocked him over as they collided, and Claude found the front of his pressed white button up splattered with a translucent sticky substance. The half cat hissed at him, the inside of its mouth glowing a bright neon blue framed with sharp fangs. 

Claude found himself frozen and the few seconds was all the time the creature needed to continue fleeing the camp. It dashed between tents, prints marring the smooth new sand before it disappeared into the tree line. 

Claude Faustus gave chase. 

If he could catch this thing, then he could show Spears that it actually existed! That Michaelis really was hiding this new species from everyone. 

He spotted the figure running just a few trees ahead, but this creature was fast, taking twists and turns that had Claude almost falling over in the undergrowth. The half cat oddly stopped for a minute and Claude frowned as he caught up to the crouching creature. It howled, voice low and almost pained, but he stepped on a twig, snapping it in half with a cliché misstep and the beast's big blue ears swivelled backwards, alerting the half cat to his presence. 

The creature sprinted again, although it seemed slower this time, the glow between its legs lit up the ground level foliage and made the ferns glow blue. Claude cursed as the creature's path led him through a patch of 'jungle dildos', tube like fly catchers that looked like human dicks planted in the ground. The immature scientists back at camp had started jokingly calling them that and the nickname irritatingly stuck. Claude thought it was entirely ridiculous, they were just plants, there was no reason to be so unprofessional, but it seemed that their lewd appearance had distracted the half cat, a few of them were torn up and crushed, perhaps in irritation. 

The creature stumbled and tripped, its cat like yowl of pain echoing through the rainforest. Faustus was finally able to catch up and he stood over the naked creature with an air of smugness. The cat thing hissed, tails swishing as its claws dug into the earth, one hand between its legs the other trying to hold itself up. Dirt and leaves caked its pale knees and dirtied its two plush ocean blue tails. 

"What are you?" Claude frowned as he adjusted his glasses, the chase had left them askew. This being was a jarring mix of human and cat, its body looked normal, but it had feline ears and tails, claws on its hands and feet, and slit cat like heterochromatic eyes. It was hard to see with the half cat curled in on itself so defensively, but between its legs were wiggling tentacle like protrusions and a massive blue glowing prick. Claude couldn't believe what he was seeing. He took a step forward and the creature pounced.

With a low hiss it tackled him and in a blur they were on the ground. It all happened so quickly, he held up his arms in defence but claws still punctured holes into his shirt. The slick from the creature's genitals burned as it seeped through his clothes and touched his skin, and he reflexively hit the creature, tried to get a solid punch in.  
He cried out as the beast bit into his shoulder and it drew blood before rolling off of him, hissing and growling and acting far more aggressive than he had originally anticipated. 

Claude held his shoulder gingerly, blood running between his fingers. The creature licked carmine from his lips. The air reeked of a bitter tang he'd not noticed before, it somehow smelt like aggression and Claude felt fear for the first time since arriving at Toboso island, not surprise, not irritation, but fear. This thing was dangerous, the many scratches now decorating his arms proved that.

He didn't notice the bug crawl up his arm. Only noticed when it was all too late and one of Toboso Island’s most deadly venomous spiders punctured his skin with iron fangs. 

He jolted, throwing the critter off and the cat creature took those few seconds of broken eye contact to sprint, run as fast as his legs would take him, as fast as his burning desire would allow him...

\--

Confusion. Pain. Loneliness. He'd never had a heat this bad before. He'd never ached this much, never felt so lonely. His legs were covered in slick by now, the potent chemicals within the velvety liquid burned even his skin and he whimpered as every step tugged on his taunt painful flesh. He collapsed against a tree, the bitter tang of blood in his mouth making him feel agitated. He struggled to dampen the feral urge to kill, the desire to wound and maim his competition, his rivals. They couldn't have him. Sebastian was his! His mate! His lover! 

The neko dug his claws into the bark, gouging out marks of jealousy into the tree's skin. His mind grew hazy, the moment of clarity dissipating, and he found himself once again thrown into the toxic heat of denied desire. 

Sebastian wasn't here…

His _mate _wasn't here!__

__Ciel growled, eyes bright and hungry, but his legs shook, the weight of his desire wearing on his tired body. He was dehydrated, and his muscles were aching from the constant tensing. He wanted to sleep. Wanted to collapse beneath the foliage and rest for an eternity, but his body still screamed at him to continue, to find his mate, to give him love and protection and sweet little kits._ _

__They'd have beautiful kits._ _

__Ciel's mind blurred, his scent turned sickly sweet and his steps held a slurred sway as he fantasised about the litter they could have. He would name one Alois, after his best friend, or perhaps Vincent? After his father, although they weren't very close. Or maybe Sebastian already had some names picked out, raising kits was a joint effort after all._ _

__The scent turned sour as Ciel remembered Sebastian's distinct absence._ _

“Seb… Sebastian” he whined pitifully, ears down turned and tails dropping between his legs. The poor thing started sobbing, big fat tears rolled down his flushed cheeks. He tried to catch the man's scent but all he could taste in his mouth was blood. _Why was there blood? _Ciel wondered, completely forgetting the earlier conflict with Faustus. And the cycle started again, that primordial rage and desire to protect his loved ones resurfaced, it was hot and sticky and made his blood boil, makes his cock throb. It overwhelmed him. The neko screamed in frustration.__

____

____\--_ _ _ _

____

____Claude was hyperventilating, his skin had quickly acquired a sheen of sweat and the bite mark had reddened but not swelled. He didn't know if that was good or bad, but he found himself unable to control his breathing. The entomologist wished he'd studied the effects of known venom more closely but found any knowledge he'd previously acquired slipping away between his unresponsive fingers. He stumbled through the forest, desperately trying to get back to camp. His slowly vision blurring._ _ _ _

____

____\--_ _ _ _

____

____“Ciel!” the scientist called out into the wind, his voice lost on the rising waves. The sun was setting, spitting orange light between darkening clouds and casting the sand in a golden glow. A storm was brewing above Toboso island. It had come out of nowhere._ _ _ _

____

____“Ciel!” he tried again but it was hopeless. His neko was nowhere in sight. They'd searched the entire camp sight, but by now Ciel could be anywhere on the island._ _ _ _

____

____“Where are you...” Sebastian's worry had only grown, bubbled and crept within him until all he could think about was the worst-case scenarios. What if Ciel was found by someone like Claude, what if neko's heat harmed him, or worse, somehow lead to his death…_ _ _ _

____

____The scientist had sent Finny and Meyrin to search opposite sides of the island but as the sun continued to set, everything just felt more and more hopeless._ _ _ _

____

____\--_ _ _ _

____

____The neko stumbled onto the beach, falling to his knees. The wind had picked up. It dragged roughly over him, playing with his ears and sending his hair into disarray. And as the sun dipped lower and lower Ciel's body continued to overheat._ _ _ _

____

____He threw up, white foam clinging to his chin, it was a wretched dry heaving that left him feeling sore. The rising tide pulled his pale vomit into the ocean and Ciel's body flooded with a renewed burst of fear. He was exhausted, dehydrated and still without his mate. He whimpered, curled up and clutched his abdomen, the endless throb of his arousal a hated feeling at this point._ _ _ _

____

____“Se-… Sebas-” the neko hiccupped, big fat watery tears staining his cheeks. He shook like a leaf, heat turning his mind to mush and leaving his stressed body floundering in hormones._ _ _ _

____

____“I've got you” Sebastian came out of nowhere and held the neko tightly, pressed his chin between Ciel's kitten ears and anchored him as he sobbed._ _ _ _

____

_Was this a dream? A hallucination? _It seemed too good to be true. His precious mate… He needed Sebastian so bad he was going insane.__

______ _ _

______“Hurts” the neko wobbled and Sebastian stripped off his jumper and shirt despite the cold wind. He quickly used them to cover the sand and guided his precious mate to lie down, all the while kissing the neko's neck and catching his reddened lips with his own chilled ones._ _ _ _ _ _

______ _ _

______This was real. Sebastian's alluring scent filled his senses and the neko managed to let out giddy purr at the closeness of his partner._ _ _ _ _ _

______ _ _

______“Seb” the neko gave him a tired smile. Ciel radiated heat and Sebastian bit back a surprised yelp as he gripped the neko's throbbing cock. Its natural slick burned in its potency, but he persisted, Ciel needed his touch._ _ _ _ _ _

______ _ _

______“You're here” the neko breathed and Sebastian answered with sweet nothings of his own, little words whispered against Ciel's lips. The neko keened as Sebastian roughly jerked him off, he mewled at the demanding tugs and bucked his hips into the relieving touch. Sebastian brought in a second hand, practically ringing out an orgasm from the tortuously horny neko. Ciel came hard, ropes of white staining his own chest and covering the zoologist's hands._ _ _ _ _ _

______ _ _

______The blue haired neko panted roughly, cock somehow still hard and glowing a toxic looking neon blue. But the pain had eased, those aching cramps in his abdomen had lessened to a more tolerable degree. And Sebastian felt his worry slowly slip away as the neko quirked his lips beneath him._ _ _ _ _ _

______ _ _

______He'd found Ciel._ _ _ _ _ _

______ _ _

______The neko watched him with blown pupils as Sebastian ran his thumb over his cheek, the scientist had to wonder how much of this Ciel would remember, he looked dazed. The cat seemed closer to a wild animal than a human right now and Sebastian was keenly aware of his glowing anatomy and inhuman features._ _ _ _ _ _

______ _ _

______The half cat observed him with lidded eyes, the heterochromatic irises filled with lust blown pupils. In any other circumstance Sebastian would have taken this time to coo over Ciel's kitten like appearance, but there simply wasn’t time. Those eyes widened when the scientist quickly started to tug off his own pants._ _ _ _ _ _

______ _ _

______Ciel mewled as Sebastian gave his cock a long slow stroke, collecting up as much of the abundant slick as he could. The half cat's claws flexed, digging into the makeshift bedding as he whined under the scientist's touch. Sebastian observed the sheen of slick covering his hand, it tingled against his skin and dripped in long sticky lines, falling in slow fat drops onto the neko's heaving chest._ _ _ _ _ _

______ _ _

There was nothing ideal about this situation, Sebastian's knees were covered in sand and they were still out in the open on the beach, but the neko _needed _him. The zoologist couldn't believe he was actually doing this. It was entirely unscientific and if anyone else on the island decided to take an evening stroll they would surely be caught with nowhere to hide.__

________ _ _ _ _

________But Ciel desperately needed his help…_ _ _ _ _ _ _ _

________ _ _ _ _

________\--_ _ _ _ _ _ _ _

________ _ _ _ _

________Like the push and pull of the waves, Sebastian bounced atop Ciel's glowing prick. The wind picked up, the neko's claws dug into his hips and Sebastian gasped as the half cat met the sway of his hips, felt Ciel's lust throb inside him, snug and tight._ _ _ _ _ _ _ _

________ _ _ _ _

________The neko purred loudly, dual coloured eyes humming lazily as he relished in the sensation of his mate above him. Little blue tentacles writhed against the scientist's backside, thighs spread atop Ciel's hips, they moved and breathed together._ _ _ _ _ _ _ _

________ _ _ _ _

________The dark clouds rumbled, the setting sun had drowned out nearly all the light and Ciel matched the sound of distant thunder with his low inhuman whine. The sea crept closer, crashing against the shore with a primal power._ _ _ _ _ _ _ _

________ _ _ _ _

________Ciel flipped them, pushing those legs up and thrusting, rocking into Sebastian like the waves hitting the sand, choppy and rough and full of desire._ _ _ _ _ _ _ _

________ _ _ _ _

________The neko glowed in the darkness, his lips and tongue, and his bright inhuman cock, lit up like he was made of magic and Sebastian moaned beneath him._ _ _ _ _ _ _ _

________ _ _ _ _

________“Oh fuck… Ciel!” the waves crashed harder, rain spitting from the sky and Sebastian felt Ciel's fingers entwine with his own. The neko anchored him, held his hand and Sebastian wrapped his legs around the half cat's hips, the twin tails brushing against his ankles._ _ _ _ _ _ _ _

________ _ _ _ _

________It started to rain._ _ _ _ _ _ _ _

________ _ _ _ _

________Small airy drops fell in the wind, one by one until it poured. The neko growled, took him harder._ _ _ _ _ _ _ _

________ _ _ _ _

________“Ciel” Sebastian moaned out. That rain picked up, fell faster, turned the sand to slush. Heavy and cold. But Ciel was so hot above him, every inch of him burned and his growls sounded like thunder. His eyes like lighting that shook the sky. So bright that Sebastian was left breathless._ _ _ _ _ _ _ _

________ _ _ _ _

________Ciel's heat filled his mind, drove him to take his mate over and over again. The scientist tried to hold on, his nails dragging red lines across the neko's back, but Ciel swept him away in the storm of his lust._ _ _ _ _ _ _ _

________ _ _ _ _

________Thunder crackled above, frightening in its intensity, their mouth met in a clash of tongue and teeth and those fangs cut his lip. Nicked the side of his mouth as they moved. The storm bubbled and brewed and poured, wet sand sticking to the scientist's back as they fucked. The cat howled, groaned against the side of his neck and bit down on his skin, held Sebastian still. That pressure built and built and finally toppled over as they both came, the neko's hips jerking to a stop and burying him deep._ _ _ _ _ _ _ _

________ _ _ _ _

________Ciel lures flashed brightly, their vibrant blue clinging to Sebastian's hips as the neko filled him up, anchored him with a claiming bite. Sebastian covered his own stomach in ropes of white, sent over the edge by Ciel's intensity._ _ _ _ _ _ _ _

________ _ _ _ _

________As one they clung to each other. Panting and exhausted and Sebastian slowly brushed aside Ciel's wet hair. Those blue locks clung to his skin and hid away his eyes. One a stunning violet, the other a soft neon blue. They were filled with love and affection and Sebastian wanted nothing more than to see them. Their lips were drawn together once more, uncaring of the rain and the thunder and the crashing waves creeping up the shore._ _ _ _ _ _ _ _

________ _ _ _ _

_Simply beautiful._

________ _ _ _ _

**Notes for the Chapter:**

> We're getting towards the end now! I just want to thank you guys for sticking with this story, it was the fisrt fic I ever posted and I've learned so much and written so much more since then, really, your support means so much to me! I wouldn't be here without you guys :')


	12. Finality

**Summary for the Chapter:**

> The boat arrives for the zoological research team stationed at Toboso island.

**Notes for the Chapter:**

> Thank you @alias-kamui (on tumblr) TheWitchingHour7 (here on ao3) for beta reading this for me! go check out their amazing mermaid sebaciel fic Adrift [LINK](https://archiveofourown.org/works/18425256/chapters/43643481)

Madam Red pulled a white sheet over the damp body, the rain certainly hadn't helped in this unfortunate incident. Claude Faustus was pronounced dead on February the 13th 2019. The current working hypothesis was that he'd gone into cardiac arrest after being bitten by something on the island. They'd found two different bite marks on him, one on his neck and the other on his arm, although the two marks looked to be from two different animals which only further confused the camp doctor.

William T. Spears had subsequently called for an immediate end to the expedition. In three days a ship would arrive to take the team back home to Sydney, where a statement would need to be given to the local authorities. William hoped that this investigation wouldn't hold up the research too much, as they would already be cutting the expedition short.

Sebastian gingerly crept into the staff meeting, taking a seat on a plastic chair near the back. Ciel was asleep in their nest (a pile consisting of his clothes and sleeping bag) it was only the second day of the neko's heat and he was still insatiable, but the regular ‘assistance’ from the zoologist eased any negative side effects he’d been feeling earlier. Sebastian just hoped he wouldn't have to stand up anytime soon, his ass was killing him and while this shitty plastic chair was uncomfortable it was way better than trying to stand.

He'd thrown on some warm clothes considering the sudden chill that had swept through the island after the storm, but it was abundantly clear to anyone paying attention that he was a complete mess. He had classic sex hair, hickies all up his neck and a somehow attractive stubble that he'd be shaving as soon as Ciel had calmed down with the constant fucking.

MeyRin was keeping Ciel company right now, he had left the tent with the neko fast asleep in her lap as she stroked his hair and played with his soft blue ears, they were getting along surprisingly well. Only MeyRin and Finny knew about the half cat and the current plan was to smuggle him aboard the ship, no one else could know about him lest he be taken away by the government for experimentation or something equally horrible.

Sebastian yawned, exhausted by the late nights and erratic sleep schedule. He'd chucked on jeans without underwear and was beginning to regret it as the denim irritated his over sensitive skin.

“I know you're all saddened by Faustus’ passing, but there is still work to be completed. Try to finish off all your reports before we leave the island. Dismissed” Spears waved them off and the other scientists slowly exited the large tent. Sebastian groaned, taking his time to stand up. Apparently taking too long as William was able to quickly approach him, the other man adjusted his glasses before speaking.

“You may be asked to make a statement on your whereabouts around the time of Claude's death, since he was supposed to be working with you”

“I understand”

“I'll not have the reputation of my research project jeopardised Michaelis” Spears narrowed his eyes.

“That won't be a problem…” Sebastian glanced over the man's shoulder at Finny who gave him a thumbs up, “I was with some of the other scientists during that time. Truly, Claude's death is a tragedy”

William didn't look impressed, but he still walked away.

\--

“Is it okay to enter, you guys decent?” Finny asked just outside the tent. He heard the scientist give a quiet yes and so unzipped the tent. Ciel purred lazily beneath Sebastian's touch and the scientist was busy scratching under his chin and rubbing one of his ears. The man had thrown on a cosy sweater but was otherwise nude, the sleeping bag however, kept his modesty. Ciel had no shame however, and lay sprawled across their nest, the fever of his heat finally calming down after 3 days of sex.

Finny passed the exhausted man a water bottle which Sebastian quickly gulped down. He was tired and sore, but it warmed his heart to see Ciel so happy and content, snuggled up with his head in the scientist's lap. Sebastian offered Ciel some water but the neko turned his nose at it, not trusting the strange object.

“How long until the ship gets here?” Sebastian asked.

“Like 6 hours, are you gonna be ready by then? Everyone is already started to pack up the camp” Finny asked in concern.

“We'll have to be” Sebastian shrugged. He didn't know how Ciel would react to packing up their nest early, but the scientist needed to clear the tent before they got on the ship.

“I managed to find the stuff you wanted” Finny passed him a plastic bag and Sebastian opened it up to reveal a large grey beanie and a pair of comfy sweatpants.

“Thanks, this should be perfect”

“Purr-fect?” Finny wiggled his eyebrows and Sebastian groaned at the joke.

\--

Ciel in fact, did not like packing up the nest before he'd finished his heat. He growled and whined while the scientist folded up shirts and packed Ciel's carefully constructed nest away into a single suitcase. And while Sebastian could ignore the pin prick of claws against the sleeve of his shirt, he couldn't ignore the water works, the crying and the sobbing that crushed his heart to hear.

“It's okay Ciel, I'm taking you somewhere else, you'll be coming with me” but his calming words didn't do much to ease the neko's sorrow. He spent an hour petting Ciel, stroking his hair and kissing his downturned lips, kissing away those salty tears, but the neko seemed inconsolable.

His hands crawled from the neko's bare back down to his rear, one hand grasping a globe of ass while the other tugged on the base of his tails. It was a cheap tactic, using sex to smooth over the neko's hurt feelings, but they were running out of time.

“I've got you, I love you” Sebastian whispered against Ciel's skin, his fingers dipped teasingly between the crevice of his cheeks and the neko whined in response. The neko’s salty tears dried momentarily as the scientist's ministrations distracted him. He pushed in close to his mate, needy and rumbling a pleased purr as Sebastian pawed at his ass and teased his entrance. Those bright neon tentacles wiggled from the confines of Ciel's body, spreading like the petals of a flower as the neko's cock quickly grew hard and slid out of its sheath.

Sebastian pushed the neko roughly to the floor, his experience with Ciel's heat teaching him to have a firm hand. He gave the already sopping cock a few rough strokes, tugging on the glowing rigid flesh and making the neko keen, before he wrapped his lips around the weeping tip. While not as overwhelming as before, Ciel's heat still lingered, still flooded his body and sweetened his scent, and as the scientist bobbed between his legs Ciel felt that smouldering fire in his gut flare and crackle. Two slick covered fingers pushed inside his tight entrance and Ciel moaned when that hot mouth slid further down his prick.

The long digits curled, and he squeaked in surprise at the feeling that jolted through him, still unused to that kind of pleasure. Sebastian rubbed and stroked him in time with his sinful mouth and coaxed thick heavy moans from the neko, his rumbly voice trailing off into a growl as the scientist sucked with renewed vigour.

Sebastian pulled off with a wet pop, slick and spit dripping from his lips, much to Ciel's disappointment. But the neko was making far too much noise, there were still other tents, other scientists nearby that could hear the neko's salacious noises. He grabbed a nearby shirt and jammed it between Ciel's fangs, muffling his lust and keeping the boy somewhat quiet as he pushed his fingers knuckle deep and swallowed his length again all the way to the base. Ciel's tentacles writhed faster, his hips bucked making the man gag around him. Sebastian's free hand pressed divots on the neko's thigh, his grip tightening in an attempt to rein in control of the half cat.

He pumped his fingers faster, dug deeper and sucked harder, and felt Ciel's length fatten in his mouth in response, its spiral texture pressing against the sides of his cheeks. His teeth scraped against the thickened girth and he swapped his mouth for a hand. The neko's whine at the loss was muffled, but he was quickly distracted with Sebastian's hands. Ciel writhed and drooled beneath him, spit and fangs digging into the fabric between his teeth.

“You're so beautiful. So perfect” Sebastian breathed out as he squeezed the neko's throbbing base. Clear tingly slick pooled between his digits as he slowly dragged his grip up and down, Ciel groaned softly, dual coloured eyes fluttering shut. The neko spread his legs further apart eagerly, wanting more.

“Such a good mate” he squeezed in a third finger, “such a good cock, such a pretty one, could suck it all day” he praised, hand picking up speed. He knew what to say to make his mate happy, what things made the neko purr, and Ciel loved compliments. He especially liked it when Sebastian praised his cock. The scientist had to assume that dicks were an important part of neko culture since they'd evolved such elaborate biology unlike anything he'd ever seen before, all in an effort to attract a mate. In Ciel's more lucid moments he'd asked what other neko's looked like, if they all glowed like he did and found out that everyone's dick was unique, however certain traits were inherited.

Ciel bucked his hips, eyes little slits of glowing blue and purple, and he flushed red and hot as Sebastian brought his mouth back to the vibrant blue tip of his length, tongue pressing just so against the weeping tip.

“Seb…” the half cat mumbled through the shirt in his mouth. He was so close, just teetering on the edge of bliss. Sebastian's tongue stroked the underside of his prick, coaxing out his pleasure and lapping up the dribbles of white like it was a treat. The neko pulled out the shirt between his teeth, tongue dry and chin damp with drool.

“Seb… claim me. You haven't done it yet” Ciel whined, eyes misty again and voice shaking with held back tears. The scientist slowed his ministrations, pulling back a bit to tilt his head questioningly.

“What do you mean?” Sebastian asked, because they'd already fucked plenty of times, and while Sebastian didn't top often, he _had _taken Ciel a few times during his heat.__

__“I claimed you” Ciel sniffled and gestured to his own neck, pressing a hand on the joint between neck and shoulder._ _

__The bite! Of course, how could Sebastian have overlooked that. The neko had repeatedly bitten him on the neck during this whole fiasco and while Sebastian had just brushed it away as the prickly nature of fucking something with feline traits, Ciel had clearly seen it as more than that._ _

__“You want me to bite you, to claim you?” Sebastian questioned as he idly rubbed his thumb over a raised line on the underside of Ciel's length. The neko pressed his hips further into Sebastian's hand, desperate for more friction, he nodded eagerly, breath whiny and rough._ _

__“m’ need you” Ciel sighed, eyelids lowered in lust._ _

__“Well then, I better fix that then” Sebastian smirked and bit down on the neko's hip. Ciel gasped as Sebastian pinched the skin between his teeth and stroked the neko to completion. Ciel bit his hand to keep quiet, eyes squeezed shut as he came, but a weak needy moan still spilled past his lips._ _

__Sebastian marked his body, bruised his hips with teeth and tongue and watched Ciel fall apart beneath him, ropes of white decorating his stomach._ _

__\--_ _

Sebastian nervously tugged the grey beanie down further, fretting over Ciel's appearance and imaging all the ways that this could go horribly wrong. The neko slapped his hand away, confident that he could blend in with the humans. _How hard could it be?_

____

____“Don't talk to anyone” Sebastian reminded him and Ciel rolled his eyes beneath his dark sunglasses, finding the zoologist's constant worrying irritating._ _ _ _

____

____“I'll be fine” Ciel gripped the man's hand tighter, claws pricking Sebastian's skin. Ciel still felt too hot and the human clothes weren't helping, his heat still lingered uncomfortably but there wasn’t a lot he could do about it. The addition of hanging around strange new humans only made his anxiety worse. Really, he didn’t know if he’d be fine..._ _ _ _

____

____Finny smiled at them, the young botanist and MeyRin approached and easily created conversation while the ship hands loaded the boat with the camp's luggage. They'd dressed him up in human clothes, had stuffed his tails down his pants legs and hid his ears with a large beanie, but he still had fangs, still had sharp eyes and deadly claws, he may have looked human, but he never would be. Ciel's eyes drifted nervously around the crowd despite his confident facade, only absently listening to Finny’s words. Sebastian dropped his hand on the neko's shoulder and Ciel found himself anchored, eyes flickering back to rest on his mate._ _ _ _

____

____There was nothing left for him on Toboso island. His people were gone, his parents, his best friend Alois, he was alone on this island. But Sebastian was his mate now and he would follow him to new lands, to a new jungle, to the man’s home, it was frightening, but worth the risk._ _ _ _

____

____Ciel let out a small purr, something quiet that only Sebastian could feel, his hand slipping down to the back of the neko's ribcage to follow its rumble. His crimson eyed human was too precious to let go, Ciel would follow the man anywhere, so long as they were together._ _ _ _

____

____“They’re boarding now, we should probably get on” MeyRin noticed and the group slowly trekked down the beach, the crunch of sand beneath shoes only foreign to Ciel. The neko squeezed Sebastian’s hand tightly and carefully stepped onto the little jetty boat that would carry them to the larger marine research vessel. They would spend the next 3 days on that boat, sailing to the port in Sydney. Ciel didn’t really know what a domestic flight was, although he’s learnt the words from his human’s lips all those weeks ago, he found he simply had no context to place them in. Sydney and Melbourne didn’t mean anything to him, they were places he’d never known had existed until a few days ago. But despite his confusion the neko was filled with a nervous excitement. This was the start of a new life._ _ _ _

____

____The jetty seemed to bounce upon the waves and Ciel marvelled at their speed, he tried to look for fish beneath the them, but the choppy bubbles of disturbed water obscured his view. Sebastian pulled him back in the boat, yanked on his fluro orange life jacket, the last thing they needed was Ciel going overboard. He chuckled at the neko’s insatiable curiosity, quietly watched Ciel fiddle with his bulky life jacket, certain that if his ears weren't obscured they’d be flickering in every direction trying to take in everything at once. Ciel really did look human, one couldn’t tell that beneath those clothes lay feline additions and Sebastian hoped that no one questioned Ciel’s presence or noticed the extra addition to the group. The neko would sleep in his room and wouldn’t require an extra bed so he could hide there if nothing else._ _ _ _

____

____Ciel tugged down his beanie again, the wind was playing with his hair and disturbing his carefully groomed appearance. He longed for the comfort of their nest, but then Sebastian pulled him in his lap and wrapped his arms around him and even though the life jackets made it somewhat awkward Ciel still felt a relaxing calm wash over him._ _ _ _

____

____It all seemed to be going to plan… although Ciel had one last concern, something he could actually focus on and think about now that his heat had dissipated somewhat._ _ _ _

____

____Kits._ _ _ _

____

____They hadn’t discussed having kits. And while Ciel wanted tiny little nekos to love and teach and father, he hadn’t asked Sebastian about it. He knew that their biology was incompatible, not to mention that they were both males, but in neko culture same sex couples usually adopted. He needed to talk to Sebastian about this._ _ _ _

____

____The neko closed his eyes and relaxed in the scientist’s arms despite his nerves. Would Sebastian even want children?_ _ _ _

____

**Notes for the Chapter:**

> Thanks for reading, kudos and comments are much appreciated! Thanks for reading my fist ever fic born solely off the idea of a glow in the dark dick, (someone had to write it).  
> Tell me what you guys thought? would anybody be interested in a few domestic oneshots?? (although I still have to write a prologue to finish this story off so this is like second last chappy)


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